Neuroterus tantulus (agamic)

Blaesodiplosis amelanchier-hook-gall

Blaesodiplosis canadensis

Eriophyes aceris

Aceria modesta

Aceria major

Vasates quadripedes

Aceria myriadeum

Melikaiella flora (sexgen)

Melikaiella ostensackeni (sexgen)

Melikaiella papula (sexgen)

Callirhytis favosa (sexgen)

Atrusca bella (agamic)

Kokkocynips rileyi (agamic)

Neuroterus quercusbatatus (agamic)

Andricus quercuspetiolicola (sexgen)

Neuroterus quercusirregularis (sexgen)

Dryocosmus quercuslaurifoliae (sexgen)

Callirhytis quercuscornigera (agamic)

Ectoedemia populella

Disholcaspis quercusglobulus (agamic)

Disholcaspis quercusmamma (agamic)

Disholcaspis globosa (agamic)

Amphibolips quercusspongifica (sexgen)

Amphibolips confluenta

Callirhytis tubicola (agamic)

Amphibolips quercusinanis (sexgen)

Macrodiplosis niveipila

Unknown q-prinoides-stem-cluster-gall

Disholcaspis q-margarettae-bullet-gall (agamic)

Philonix fulvicollis (agamic)

Druon quercusflocci (agamic)

Philonix lanaeglobuli (agamic)

Andricus robustus (agamic)

Druon laceyi (agamic)

Unknown d-texana-blister-gall

Disholcaspis cinerosa (agamic)

Disholcaspis fungiformis (agamic)

Loxaulus pattersoni (agamic)

Neuroterus bussae (sexgen)

Neuroterus q-virginiana-numerous-leaf-galls (agamic)

Neuroterus saltatorius (texanus) (agamic)

Unknown q-virginiana-acorn-gall

Unknown q-virginiana-hollow-bud-gall

Andricus highlandensis (sexgen)

Unknown q-virginiana-root-gall

Loxaulus virginianae (agamic)

Unknown q-virginiana-white-cell-twig-swelling

Acraspis echini (agamic)

Callirhytis seminator (sexgen)

Unknown q-myrtifolia-erineum-mite

Callirhytis quercusfutilis (sexgen)

Callirhytis quercusfutilis (agamic)

Callirhytis gallaestriatae (agamic)

Callirhytis q-stellata-pentagonal-cluster (agamic)

Unknown q-ilicifolia-fuzzy-yellow-spangle

Zopheroteras hubbardi (agamic)

Unknown q-rubra-globular-vein-gall

Unknown s-lanuginosum-bead-gall

Unknown q-alba-red-hairy-bead-gall

Phylloteras q-muehlenbergii-spangle-gall (agamic)

Phylloteras q-stellata-spangle-gall (agamic)

Unknown q-montana-fuzzy-sphere-cluster (agamic)

Unknown q-alba-truncate-petiole-cluster

Andricus weldi (agamic)

Unknown q-alba-hairy-petiole-cluster

Unknown q-velutina-fuzzy-vein-globs

Unknown ash-leaf-bunching

Callirhytis glandulus (agamic)

Andricus incertus (agamic)

Unknown q-phellos-leaf-club

Celticecis capsularis

Celticecis pubescens

Celticecis spiniformis

Celticecis conica

Celticecis subulata

Celticecis acuminata

Celticecis oviformis

Celticecis celtiphyllia

Celticecis expulsa

Pachypsylla pallida

Walshomyia cupressi

Pachypsylla celtidisvesicula

Pachypsylla celtidismamma

Unknown t-americana-tuft-gall

Unknown c-reticulata-raised-bark-gall

Callirhytis quercusagrifoliae (sexgen)

Neuroterus quercusbatatus (sexgen)

Unknown q-stellata-nipple-spangle

Callirhytis quercussuttoni (sexgen)

Melikaiella flora (agamic)

Pachypsylla celtidisgemma

Pachypsylla celtidispubescens

Pachypsylla celtidisglobula

Pachypsylla celtidiscucurbita

Pachypsylla laevovesicula

Pachypsylla reticulovesicula

Pachypsylla rugosa

Unknown q-rubra-stellate-bud-gall

Diaspidiotus liquidambaris

Visually similar to Neuroterus saltarius, which occurs on Quercus bicolor and macrocarpa rather than alba and stellata.

Could be confused with the undescribed bead gall also found on Quercus alba, which is a similar size and density but lacks the distinct raised edge and dimple form of N tantulus.

Quercus chapmanii added tentatively as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/110837258).

Quercus muehlenbergii added tentatively as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/153131583).

When originally described by Stebbins (1910) this gall was presumed to be induced by an eriophyid gall. However, no mite has been described from the galls and similar galls on Amelanchier have been found to contain midges of the genus Blaesodiplosis.

Plausibly a synonym of Blaesodiplosis canadensis, though also plausibly a distinct species. The morphological differences between the two are not clear based on photos and descriptions in the literature. 

Nearly all observations on iNaturalist of this species are fuzzy galls in the Pacific Northwest. To our knowledge, no sources in the literature indicate this species is fuzzy, and its reported range (see Gagne 2017) is limited to the northeast US. Further study may reveal that these are in fact the same species, but it may also indicate multiple species with distinct morphologies in the two regions. 

The name "Aceria aceris" is current for this mite but that name is already used for a different species found in Europe. Amrine suggests the name be changed to Aceria hodgkissiae but that change has not been made in the published literature yet. 

Host association with Acer floridanum is a supposition made based on its close relationship to Acer saccharum and the appearance of a similar gall on A floridanum in [this iNaturalist observation](https://www.inaturalist.org/observations/46335294). Further investigation may find this is a distinct mite species.

Hodgkiss described three mite species from erineum on the lower surface of Acer rubrum leaves, of which Aceria major and Aceria quinquilobus remain valid species (Eriophyes ornatus is a junior synonym of A major). These are either distinct species forming similar galls, in which case it is not clear how the galls might be distinguished, or an inducer-inquiline pair, in which case it is not clear which is the inducer. All current observations have been placed in Aceria major.

Amrine lists this mite on Acer pseudoplatanus based on a report in Batchelor G.S. 1952. The Eriophyid mites of the state of Washington. Wash. Agric. Exp. Stn., Tech. Bull., 6: 1-32. ; I believe this report is likely mistaken and the galls were instead formed by Aceria cephalonea. 

Galls formed by this mite on Acer saccharinum tend to be larger, more wrinkled, and redder, while those on Acer rubrum are tight, beadlike, and tan. 

The taxonomic status of beadgall forming mites on Acer campestre and pseudoplatanus is currently unclear and quite confusing. The European gall site Bladmineerders lists at least three species: Aceria cephalonea on A campestre and pseudoplatanus, Aceria macrorhyncha on A pseudoplatanus and "rarely" on A campestre, and Aceria myriadeum on A campestre. Amrine, however, lists both Aceria macrorhyncha and Aceria cephalonea as junior synonyms of A myriadeum, implying there is one mite responsible for a range of upper-leaf bead and nail gall forms on both hosts. 

For the moment, our taxonomy follows the Amrine catalog, while IDs on iNaturalist largely follow Bladmineerders. However, note that while galls similar to images Bladmineerders presents as Aceria cephalonea have been observed on Acer pseudoplatanus in North America, to our knowledge no anatomical IDs have been made of the mites on either Acer species outside of Europe. Any ID made of galls here is thus doubly uncertain. 

A gall matching the description of this species has been frequently observed on trees identified as Shreve oak, Quercus parvula var shrevei, which is known to hybridize with its known hosts. However, this relationship has not been confirmed by rearing to our knowledge.

[Melikaiella papula](https://www.gallformers.org/gall/753) and [Melikaiella ostensackeni](https://www.gallformers.org/gall/748) form similar galls on the same set of hosts, and at the moment no reliable method is known to distinguish them. M papula and M ostensackeni were confirmed to be distinct wasp species by Pujade-Villar et al, but the description they give of the galls formed by each species is the same. 

[Callirhytis favosa](https://www.gallformers.org/gall/757) also forms integral leaf galls on red oaks, but can be distinguished by its much greater thickness and more circumscribed habit, not sprawling in numbers across the leaf as the Melikaiella galls do.

Quercus ellipsoidalis added tentatively as a host based on [these unconfirmed observations](https://www.inaturalist.org/observations/96028087) [(2)](https://www.inaturalist.org/observations/98839068) [(3)](https://www.inaturalist.org/observations/96028086).

[Melikaiella papula](https://www.gallformers.org/gall/753) and [Melikaiella ostensackeni](https://www.gallformers.org/gall/748) form similar galls on the same set of hosts, and at the moment no reliable method is known to distinguish them. M papula and M ostensackeni were confirmed to be distinct wasp species by Pujade-Villar et al, but the description they give of the galls formed by each species is the same. 

[Callirhytis favosa](https://www.gallformers.org/gall/757) also forms integral leaf galls on red oaks, but can be distinguished by its much greater thickness and more circumscribed habit, not sprawling in numbers across the leaf as the Melikaiella galls do.

Atrusca bella, brevipennata, simulatrix, and potentially other related wasps form superficially identical galls on an overlapping list of hosts. They are apparently only distinguishable by anatomical analysis of adult wasps.

Quercus georgiana added tentatively as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/92180722). 

Quercus pagoda added tentatively as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/138760547). 



Neuroterus quercusbatatus winter (agamic generation) galls on Quercus alba are most likely to be confused with Callirhytis clavula. C clavula galls are always found at the very tip of the growing twig, beneath the buds, with a distinct club-shaped taper. N quercusbatatus galls occur along the stem and have a much more irregular form.

On hosts other than Quercus bicolor, because both agamic and sexual generation galls occur primarily on "stems," the two generations can be somewhat difficult to distinguish when no longer fresh. Fortunately this is not necessary for a species-level ID. Beutenmuller's illustrations are not labelled to distinguish the generations so all 8 are included in both pages. 

There may be some morphological overlap between the fleshy sexual generation ["Neuroterus noxiosus"](https://www.gallformers.org/gall/1339) galls on the petioles and midribs of Quercus bicolor leaves and Andricus quercuspetiolicola. Most A q. petiolicola galls are clearly distinguishable by their large size, smooth surface, lack of leaf deformation, and conical shape ending in a pronounced indentation. However, some galls that otherwise seem to match Neuroterus noxiosus have fairly regular spherical shapes that could theoretically be confused with A q. petiolicola galls, especially after the wasps have emerged and the galls have begun to dry out. 

Quercus lyrata added tentatively as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/116325757). 

The host relationship with Quercus michauxii is likely, inferred based on its close relationship with all of this wasp's other hosts, but not confirmed by rearing an adult specimen.

This species is considered likely to be the sexual generation of "Neuroterus saltatorius" bead galls on white oaks in eastern North America, including Kinsey's [Neuroterus saltatorius australis](https://www.gallformers.org/gall/1076) on Quercus stellata and the [white bead gall](https://www.gallformers.org/gall/1071) on Quercus alba and others.

Quercus oglethorpensis is added tentatively as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/110756445).

Plausibly but not definitely a synonym of Drycosmus quercuspalustris. Weld lists D q laurifoliae on Q phellos and laurifolia, Krombein on Quercus nigra and laurifolia, but both assert D quercuspalustris is on "all red oaks," which would include all three of those hosts as well. No differences in gall morphology are known. 

The Weld book implies that C quercuscornigera and C quercusclavigera are morphologically indistinguishable for much of their life cycles but can be distinguished by host oak species. However, the Melika and Buss paper places C quercuscornigera on all of the hosts Weld mentions for either species, removing that as a definitive character. C quercuscornigera  is the only one of the pair reported on most of the hosts, but on Quercus laurifolia and phellos (and possibly on other related oaks), galls could be caused by either wasp. 

Old or damaged specimens of C quercuscornigera are difficult if not impossible to distinguish from C quercuspunctata by gall morphology alone. 

Frequently, even more often than not, confused with Pemphigus populicaulis, but easily distinguished by its brown-gray color, its split, almost bark-like texture made of dozens of tiny vertical stretch marks, its regular, uncontorted shape, its placement at the base of the leaf, and its lack of an obvious seam. E populella galls also tend to be smaller. 

Pemphigus galls often twist and distort the petiole, vary in their placement along the petiole, have a smooth green-red surface (occasionally flecked with white), and often show a seam, occasionally split enough to see the inside of the gall. Opening the gall will easily confirm either way, as the inside of a Pemphigus gall is full of dozens of tiny white aphids. 

Disholcaspis quercusglobulus is most commonly confused with Disholcaspis quercusmamma. The simplest way to tell them apart is by the identity of their host plant. However, when host ID is uncertain, they can also be fairly reliably distinguished by morphology (and even used to ID their host oak). 

Disholcaspis quercusglobulus is almost always found at the nodes of Quercus alba twigs, typically in groups of 1-4 arranged around the circumference of the node. It has a smooth, hairless texture often roughened by raised gooseflesh points, becoming minute splits as the gall matures. Its shape is typically almost perfectly spherical except for its attachment to the twig, but nipple-like points do occasionally occur, so this trait is not definitive. It occasionally softens or wrinkles, especially in galls that don't develop fully, but more typically holds a firm spherical shape after wasps have exited. Infrequently, galls have been seen to fuse with adjacent galls. 

Disholcaspis quercusmamma, conversely, is often found in groups of a dozen or more arranged along the length of Q bicolor or more often Q macrocarpa twigs, often dense enough to deform adjacent galls. The distinctive ridges of Q macrocarpa twigs surrounding these galls are often the easiest way to identify the species. Its texture is velvety when young and leathery when old, often rough but never showing the minute splits found on Disholcaspis quercusglobulus. Galls typically but not universally have a pronounced nipple. Many clusters of galls, especially early in the season, include small undeveloped galls that are more conical than globular, something never seen with D quercusglobulus. After wasps have exited galls, frequently wrinkle or collapse to varying degrees.

On Quercus alba, Disholcaspis quercusglobulus can be confused with Disholcaspis globosa. Weld lists this species as a "root" gall, and it is typically found in clusters where young trees meet the surface of soil, often concealed by leaf litter. But it is apparently found on nodes or along the stems of young sprouts and occasionally at the base of lateral branches of mature trees as well, where it might be confused with Disholcaspis quercusglobulus. Aside from its location, it can be distinguished by its deep red color (though both species are yellow/pink when immature) and more haphazard distribution around stem nodes in larger numbers than is typical for Disholcaspis quercusglobulus. Disholcaspis globosa also seems to be more velvety in texture and lack the raised points/splits of Disholcaspis quercusglobulus.

Disholcaspis quercusmamma was not reported on Quercus muehlenbergii in the literature, but similar galls have been reported on that host somewhat frequently, and adults reared from these galls by [Ward et al](https://www.gallformers.org/source/691) were most closely related to that species, and galls shared its habit of growing along the stem rather than at the node as in D quercusglobulus. 

D q mamma is most commonly confused with D q globulus. The simplest way to tell them apart is by the identity of their host plant. However, when host ID is uncertain, they can also be fairly reliably distinguished by morphology (and even used to ID their host oak). 

D q mamma is often found in groups of a dozen or more arranged along the length of Q bicolor or more often Q macrocarpa twigs, often dense enough to deform adjacent galls. The distinctive ridges of Q macrocarpa twigs surrounding these galls are often the easiest way to identify the species. Its texture is velvety when young and leathery when old, often rough but never showing the splits found on D q globulus. Galls typically but not universally have a pronounced nipple. Many clusters of galls, especially early in the season, include small undeveloped galls that are more conical than globular, something never seen with D q globulus. After wasps have exited galls, frequently wrinkle or collapse to varying degrees.

D q globulus is almost always found at the nodes of Quercus alba twigs, typically in groups of 1-4 arranged around the circumference of the node. It has a smooth, hairless texture often roughened by raised gooseflesh points, becoming minute splits as the gall matures. Its shape is typically almost perfectly spherical except for its attachment to the twig, but nipple-like points do occasionally occur, so this trait is not definitive. It occasionally softens or wrinkles, especially in galls that don't develop fully, but more typically holds a firm spherical shape after wasps have exited. Infrequently, galls have been seen to fuse with adjacent galls. 

D globosa is typically mistaken for its far more apparent cousin D q globulus, also found on Quercus alba. The most reliable way to distinguish them is by location. Weld lists D globosa as a "root" gall, and it is typically found in clusters where young trees meet the surface of soil, often concealed by leaf litter. However, D globosa is apparently found on nodes or along the stems of young sprouts and occasionally at the base of lateral branches of mature trees as well, where it might be confused with D q globulus. Aside from its location, it can be distinguished by its deep red color (though both species are yellow/pink when immature) and more haphazard distribution around stem nodes in larger numbers than is typical for D q globulus. D globosa also seems to be more velvety in texture and lack the raised points/splits of D q globulus. Some galls may not be definitively identifiable as one or the other without rearing adult wasps. 

This species is the most commonly observed cynipid gall in the eastern US, and readily recognized by its size, placement, and spongy interior. There is substantial taxonomic confusion in the distinction between A confluenta and A quercusspongifica. Osten Sacken described three species--aciculatus, spongifica, and coccinea--which he distinguished based on host species, gall morphology, and emergence timing. Walsh subsequently conducted a large-scale rearing program of galls from Quercus velutina at a single site in Illinois, all fresh in May. He found that the galls differed morphologically between two endpoints, and that the emergence timings clustered clearly into two periods: sexgen adults in June, agamic females from September to November, with some emerging in the subsequent spring. However, he observed that both gall morphologies were found in both emergence periods, and noted a range of intermediate forms suggesting there was no consistent distinction to be drawn between them. He concluded that they were alternating generations of the same species, of which the agamic females in the fall laid unfertilized male eggs and the mated sexgen females in the summer laid female eggs, both of which hatched in the subsequent spring. 

Walsh later apparently conducted experiments that he and Beutenmuller took as definitive confirmation of this hypothesis, which he published, synonymizing quercusspongifica as the sexgen form of Amphibolips confluenta. His experiments involved placing agamic females reared in October onto trees he understood to be isolated and not previously host to Amphibolips. While his host trees were not isolated from oviposition by other wasps, if his assumption that no other oviposition is remotely likely is accepted, Walsh's results show that oviposition by agamic wasps in the fall produces identical galls the following spring from which emerge both sexgen females in June and agamic females in the fall, and that these agamic females in turn lay eggs that produce sexgen females in the following spring. It is noteworthy that Walsh's experiments produced no males even from the sexgen galls, though this may be a coincidence given the small numbers of wasps he successfully reared. Further, Walsh was never apparently able to record the results of oviposition by sexgen females (perhaps due to this lack of males?). 

Kinsey considered Walsh's research inadequate because no oviposition was documented, and Weld treated spongifica and confluenta as distinct species pending "further study" but noted they are "probably" synonyms. 

The hypothesis Walsh put forward is highly unusual relative to every closed life cycle published since. There are several known cases in which sexual generations become facultative or discarded entirely, with agamic females emerge from agamic galls and laying eggs that become agamic females inducing agamic galls. However, in all such documented cases, the sexual generation gall is very different from the agamic gall, sometimes even occurring on a different host section. In Walsh's hypothesis, the sexgen and agamic galls are indistinguishable in host, phenology, and appearance. 

Additionally, by analogy with related species, it is surprising that the sexgen females emerging in June would oviposit in tissues during the growing season but not take advantage of the plant's growth to create a new gall until the following spring. [Amphibolips quercusinanis](https://www.gallformers.org/gall/582), for instance, is a sexual generation gall similar to quercusspongifica that emerges and oviposits in June. Unconfirmed genetic evidence suggests that the eggs it lays immediately cause the subsequent growth of galls of [Amphibolips cookii](https://www.gallformers.org/gall/1143), which produce agamic females in the fall which oviposit in buds before winter. Assuming that Walsh's evidence is true to the extent he was able to confirm, it is conceivable that this species produces another, distinct agamic gall in the fall.

On red-group oaks, A confluenta/quercusspongifica is commonly confused with A quercusinanis, which also occurs on leaves in the spring but which has a uniformly smooth exterior with distinct spots, A quercusostensackenii, which is much smaller and doesn't distort the host leaf, and A cookii, which occurs on buds in the fall and has larger spots and thicker walls. A confluenta typically has a bumpy surface. The most definitive way to distinguish it is to note the spongy interior; A quercusinanis and A quercusostensackenii has a stringy, empty interior, while A cookii has thick, succulent fibers. 

Some specimens that otherwise resemble A confluenta do have spots. This may represent a different species but is more likely a host- or generation-related variation (these spotted variants are typically but not definitively or exclusively associated with Quercus buckleyi, shumardii, pagoda, and velutina).

A confluenta/quercusspongifica early in the spring can also be confused with Dryocosmus quercuspalustris, which also forms green, spherical, integral leaf galls that distort leaves. The galls are easily differentiated by their internal structure, which can be observed by shining a bright light through the gall or but cutting it open. D quercuspalustris has a loose larval cell freely rolling around in an otherwise empty chamber. D quercuspalustris galls are much smaller and differ subtly but distinctly in texture. A confluenta/quercusspongifica galls almost always completely deform their host leaves, to the extent that they are often barely visible, while D quercuspalustris galls may seem to almost completely displace the leaf (especially early in leaf out) or have minimal effect on its overall structure (later in the season). 

A distinct but similar gall is induced by a wasp originally described as [Andricus texanus](https://www.gallformers.org/gall/3367). This wasp was made a junior synonym of Callirhytis tubicola in the 1951 Krombein catalogue, and has not been treated separately by any subsequent literature. However, recent examination of the wasps by [Miles Zhang](https://www.inaturalist.org/observations/30756251#activity_comment_c4206cdb-ba88-4ac7-8acb-5cd3c7e67029) suggests that this synonymy should be reversed. Pending formal publication of that change, Andricus texanus remains a junior synonym of C tubicola.

The galls also differ in known range. Andricus texanus has only been reported in Texas, while Callirhytis tubicola is only known from Washington DC and South Carolina. 

According to genetic results in the Ward et al 2022 phylogeny, [Amphibolips cookii](https://www.gallformers.org/gall/1143) is likely the alternate generation of the same species that induces [Amphibolips quercusinanis](https://www.gallformers.org/gall/582). In the table where this speculation is listed, A cookii is labelled as a sexual generation and A quercusinanis as an agamic gall, but this is contradicted by prior literature and may be a mistake.

Amphibolips quercusinanis is a common and distinctive gall found throughout the range of Quercus rubra. It is most commonly confused with Amphibolips confluenta/quercusspongifica, which is larger, more frequently aborts its host leaf, and tends to lack spots and have a bumpier, thicker shell. However, these characters can be misleading, and the most decisive way to tell the species apart is by comparing the internal structure. Amphibolips quercusinanis has an empty interior full of smooth, radiating strings, where confluenta has an interior either densely packed with spongy material or at least with spongy fibers. The presence of spots is especially misleading toward the southern edge of its range, where confluenta is apparently more likely to have spots and quercusinanis is less likely to occur at all. 

It can also be confused with Amphibolips quercusostensackeni, especially early in the spring, which has a similarly thin shell and empty interior with smooth fibers, but which lacks spots, remains much smaller throughout the season, and does not distort the host leaf. 

In the fall, Amphibolips cookii is often mistaken for quercusinanis. Both galls have spots and lack a spongy interior, but can be distinguished by their placement (cookii is found on buds, not leaves), their appearance (cookii has thicker, more succulent walls and fibers), and most easily by their season of appearance (cookii in the fall, quercusinanis in the spring).

In some parts of its range, Amphibolips quercusinanis co-occurs with Atrusca quercuscentricola, an oak apple of similar size, pattern, and structure found on Quercus stellata.  Aside from its host, which is often not apparent if the gall is found on the ground, Atrusca quercuscentricola has a more yellow-orange appearance and red spots, light pubescence, and occurs in the fall. It is common in Arkansas and Missouri, where Amphibolips quercusinanis is found but relatively rare. 

The gall of this species has [at least once](https://www.inaturalist.org/observations/82541020) been found on the flower stalk rather than the leaf.

Similar galls have been noted from both red and white group oaks across the eastern US and Canada, and current research is not sufficient to confirm whether these galls are all necessarily formed by the same species across all hosts. Host associations beyond the type host (Quercus alba) are based on unconfirmed observations and should be considered tentatively associated with this specific fly species. 

Quercus hemisphaerica added tentatively as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/110335527). 

Observations tentatively associated with this species have been made in [Tennessee,](https://www.inaturalist.org/observations/15738652) [New York,](https://www.inaturalist.org/observations/7700422) and [Pennsylvania](https://www.inaturalist.org/observations/33496044) [2](https://www.inaturalist.org/observations/58097634) [3](https://www.inaturalist.org/observations/58113215) [4](https://www.inaturalist.org/observations/63575208). They apparently [sometimes](https://www.inaturalist.org/observations/77599553) persist on the stem into the next spring.

Quercus muehlenbergii added tentatively as a host based on its relationship to Q prinoides and on [this observation](https://www.inaturalist.org/observations/94512447). 




The taxonomy of this species seems considerably confused. Bassett described Cynips rugosa on Quercus prinoides, with characteristics that seem to match Disholcaspis globosa (found on several closely related oaks) more than quercusglobulus (distinctions that led him to name it a new species). Weld's picture, taken on Quercus margarettae, also seems to resemble D globosa, as does that of Stebbins. However, by 1951 Cynips rugosa had been synonymized into Disholcaspis quercusglobulus. It isn't clear who did this or on what grounds. Weld seems to disagree with this synonymy, given the fact that his picture refers to it as a third, undescribed species, found on Quercus margarettae and prinoides (though not listed in his main text for either species). 

The taxonomy of this genus is somewhat confused and may still be unresolved. Six original species descriptions were made: fulvicollis, nigricollis, lanaeglobuli, niger, gillettei, and gigas. Of these, fulvicollis and nigricollis were described from adults alone, while the others were described from adults reared from similar spherical felted galls. Beutenmuller mistakenly synonymized Acraspis erinacei and Philonix fulvicollis, and Kinsey followed his synonymy in 1920 but reversed this in 1929. Kinsey's 1929 book treats the entire genus as "Cynips fulvicollis," with fulvicollis, nigricollis, niger/nigra, and gillettei all synonymized as var fulvicollis, gigas and lanaeglobuli as distinct varieties, and with var canadensis, major, rubricosa, and vorisi added as new varieties (which he claims Weld mistakenly assigned to Philonix nigra). 

Later work is inconsistent in accepting Kinsey's synonymies. Weld uses the name Philonix nigra for everything Kinsey assigns to fulvicollis, excepting lanaeglobuli and gigas. Krombein in 1979 lists both fulvicollis and Kinsey's varieties thereof as valid, but ignores his demotion of gigas and lanaeglobuli to variety status and retains nigra and nigricollis as valid. 

According to Scott Digweed (personal communication), fulvicollis is the valid name and P nigra should be considered a junior synonym. 

Galls that persist on leaves through the winter lose their pubescence and shrink somewhat, and can be confused with Acraspis pezomachoides on Quercus alba. While their surface may become wrinkled, it remains smooth, unlike any Acraspis gall. 

Galls have been observed that resemble Philonix nigra in every respect except that their interior structure is hollow rather than succulent or fibrous throughout. These are presumed to be P nigra galls affected by an inquiline. This phenomenon has been observed eg on galls on Quercus alba in Maryland in [June](https://www.inaturalist.org/observations/83906352) [(2)](https://www.inaturalist.org/observations/83415333). Similar galls were observed on Quercus macrocarpa in Michigan in [October](https://www.inaturalist.org/observations/96854737) containing live chalcidoid larvae. 

Most often confused with Andricus pattoni on Quercus stellata, which tends to be more loosely tufted and tan-brown, while Andricus quercusflocci is often more tightly packed and orange-tinted. However, host ID is the only reliable way to distinguish the galls.

This gall has been [observed](https://www.inaturalist.org/observations/92831287) and many other times on a stem of Quercus alba.

Quercus michauxii added tentatively as a host based on [this and several other unconfirmed observations](https://www.inaturalist.org/observations/105175706).

Weld has this species reported from Florida, but his given host, Quercus bicolor doesn't occur in Florida. This seems to be the result of some taxonomic confusion, with Beutenmuller interpreting Ashmead's "Quercus bicolor" as a then-deprecated synonym of his Quercus platanoides, now the modern Quercus bicolor. It seems most likely that Ashmead's trees were what we now call Quercus michauxii, which has at points been called Quercus bicolor var michauxii. 

No Philonix galls have been reported in Florida apparently since Ashmead's original description. Weld, Kinsey, and Beutenmuller only list this species based on the specimen collected by Ashmead and no observations matching this gall appear in Florida on iNaturalist or Bugguide.  

A [similar gall](https://www.gallformers.org/gall/2910) has been found on Quercus macrocarpa in Ohio, Illinois, and Indiana.

The taxonomic history of this species is somewhat confused; see ID notes for [Callirhytis vaccinii](https://www.gallformers.org/gall/575). 




Small clusters of 1-10 individual brown oval cells in the center of the leaf, emerging perpendicular from the midrib on both upper and lower leaf sides of Quercus laceyi in the fall. Seen in abundance on nearly every leaf. The cell surface when examined with a microscope shows numerous minute papillae covered with a crystaline material and sparse long white woolly hairs. The hairs come off as the galls age, except near the base. Inside is a single thin-walled chamber. Cells stay firmly attached to the leaf when it falls. Leaf petioles frequently display a small darkened area, presumably where eggs were inserted. Approximately 2-3mm long and 1.5mm in diameter. Seen in Fort Worth, TX in October. Adults emerge the following February.

Observations are collected in [these Similar Observation Sets](https://www.inaturalist.org/observations?verifiable=any&place_id=any&field:Similar%20observation%20set=Q.%20laceyi%20gall%20and%20inquilines) [(2)](https://www.inaturalist.org/observations?verifiable=any&place_id=any&field:Similar%20observation%20set=postoak_gumdrop) on iNaturalist.


Green, fuzzy erineum pockets formed on the upper surface of Diospyros texana leaves in spring, persisting throughout the year. 

This gall is often presumed to be formed by Aceria theospyri, the mite causing erineum galls on Diospyros virginiana. As the mite is to our knowledge undescribed, this may turn out to be the case but there is no reason to believe it at the moment. It is just as if not more likely to be a distinct species. It is, like its host, limited in range to Texas and, likely, northern Mexico.


Association with Quercus geminata possible based on the ambiguous implication in Weld 1959 that the entire list for Quercus virginiana also occurs on Quercus geminata, but not confirmed by later sources.

Association with Quercus fusiformis inferred from iNaturalist observations.

In the literature, this species was originally described from a "variety of Quercus virginiana" found in Texas. It is not listed on Quercus virginiana by more recent sources and iNat observations have only been seen on trees identified as Quercus fusiformis in Texas. 

Association with Quercus geminata possible based on the ambiguous implication in Weld 1959 that the entire list for Quercus virginiana also occurs on Quercus geminata, but not listed in any other source and therefore not included in our entry.

Association with Quercus geminata based on the ambiguous implication in Weld 1959 that the entire list for Quercus virginiana also occurs on Quercus geminata.

Quercus fusiformis added as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/63500228). 

Melika et al 2021 describe N bussae only from specimens collected in Florida. [An adult male](https://www.inaturalist.org/observations/112870734) reared from [a gall resembling N bussae](https://www.inaturalist.org/observations/112185188) in Austin, TX appears to match the male description given for N bussae in Florida, supporting the assumption that this same species is found outside of Texas. 

In the description given by Melika et al, emergence holes are noted to be typically found on the upper side. Given the high prevalence of inquilines in these galls, it is possible that emergence holes on the lower side may be caused by those species rather than the inducer.

Neuroterus bussae can be confused with the oviposition scars of [Belonocnema](https://www.gallformers.org/gall/710) leaf galls, which are found on live oak leaves in the spring during the same period as N bussae galls develop. [Belonocnema oviposition scars](https://www.inaturalist.org/observations/112174581) are extremely numerous, often nearly a dozen on each leaf of a sprout of new leaves. The two are most easily distinguished from the upper side of the leaf, where N bussae produces a raised bump. N bussae galls do not cause holes in the leaf, as Belonocnema ovipositors often do. 

Association with Quercus geminata possible based on the ambiguous implication in Weld 1959 that the entire list for Quercus virginiana also occurs on Quercus geminata, but not listed pending a confirming report on that host. 

Weld lists this species separately from [Neuroterus saltatorius texanus](https://www.gallformers.org/gall/1109) but the only apparent distinction between the two is that this species drops in April rather than the fall. They may the same species. 

Association with Quercus geminata based on the ambiguous implication in Weld 1959 that the entire list for Quercus virginiana also occurs on Quercus geminata.

This wasp is one of two species (along with [Andricus quercuslanigera](https://www.gallformers.org/gall/895)) apparently native to the southeast US that has been imported to Quercus virginiana planted in California. The identity of the wasp has not been confirmed, however.

Association with Quercus geminata based on the ambiguous implication in Weld 1959 that the entire list for Quercus virginiana also occurs on Quercus geminata.

Quercus fusiformis added tentatively as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/99881683).

Weld's gall is only associated with Quercus geminata based on the ambiguous implication that the entire list for Quercus virginiana also occurs on Quercus geminata. Conversely, [Melika et al 2021](https://www.gallformers.org/source/396)'s Andricus highlandensis is only described from Quercus geminata. It is possible that further research will show that the galls on other live oaks are induced by distinct species. 

Weld has this species reported from Florida, but his given host, Quercus bicolor doesn't occur in Florida. This seems to be the result of some taxonomic confusion, with Beutenmuller interpreting Ashmead's "Quercus bicolor" as a then-deprecated synonym of his Quercus platanoides, now the modern Quercus bicolor. It seems most likely that Ashmead's trees were what we now call Quercus michauxii, which has at points been called Quercus bicolor var michauxii. 

Kinsey lists Ashmead's echini as a variety of his Cynips pezomachoides, known only from Ashmead's specimen. He also lists a distinct species, Cynips gemmula agamic form, that is apparently not described in any other known sources (to the extent that it differs from Acraspis prinoides). Given the confusion around Ashmead's host determination for Acraspis echini, it seems unlikely that these represent distinct valid species, and Kinsey's Cynips gemmula (excluding Acraspis prinoides) is taken to represent the same gall Ashmead described as Acraspis echini. 

Weld lists this species as a stem gall, and this is how it is typically perceived, but observations made early enough in spring will show that it is in fact a bud gall. This is why it is most often found at the terminus of twigs. Galls found elsewhere on the stem emerge from lateral buds.

Callirhytis seminator is most frequently confused with Callirhytis quercusoperator, a catkin gall on red-group oaks. Aside from the absence of catkins and host ID, Callirhytis seminator can be distinguished by its regular pink-turning-brown spots and more regularly sphere-like shape. 

It may also be confused with Andricus aciculatus, a stem gall on Quercus stellata. Andricus aciculatus has much denser wool, often condensing to a near-impenetrable felt when wetted, and lacks pink or brown spots entirely. 

Raised blisters on leaves of Quercus myrtifolia containing erineum below. Seen in April in [Florida](https://www.inaturalist.org/observations/43654386) and in [Louisiana](https://www.inaturalist.org/observations/69187444) and [Alabama](https://www.inaturalist.org/observations/69919614) [(2)](https://www.inaturalist.org/observations/70151074) in February.

The agamic generation of this species is also known from Quercus prinoides and possibly Quercus stellata, suggesting the sexual generation could be found on those oaks as well. An observation consistent with this description has been found on Quercus stellata in May in [Texas](https://www.inaturalist.org/observations/78708815).

Quercus michauxii added as a host based on the wide host range within white oaks otherwise known for this species and based on [this unconfirmed observation](https://www.inaturalist.org/observations/42978811).

The sexual generation of this species is also known from Quercus bicolor, macrocarpa, and lyrata, suggesting the agamic generation could be found on those oaks as well. 

Technically a lateral bud gall but often when mature the bud is no longer evident and the gall appears as a stem gall. Stebbins and Weld list this as a fall gall but galls matching its description have been more frequently seen in the spring. 

This may be Beutenmuller's Andricus impositus, which was described from specimens collected near New York City but which Weld later synonymized with [Callirhytis vaccinii](https://www.gallformers.org/gall/575), a gall only known from Texas. See ID notes for [Callirhytis vaccinii](https://www.gallformers.org/gall/575). 

[According to Dr. Andrew Forbes](https://www.inaturalist.org/observations/8265894#activity_comment_762c68b7-0c2b-4770-aacb-190a48fef03c), an adult reared from this gall was determined to be a sister species of Callirhytis vaccinii through genetic analysis.

Quercus austrina added as a host based on [this observation](https://www.inaturalist.org/observations/133240894).

Small, fuzzy, yellow spangles with thick, woody walls on veins on the underside of Quercus ilicifolia leaves. Never reared but each containing a single cynipid larva. Known from five observations in State College Pennsylvania on July 30, 2020: [1 (including cross section)](https://www.inaturalist.org/observations/54850407) [(2)](https://www.inaturalist.org/observations/54851081) [(3)](https://www.inaturalist.org/observations/54850709) [(4)](https://www.inaturalist.org/observations/54849994) [(5)](https://www.inaturalist.org/observations/54852104).

A similar gall has been observed on an undetermined red oak in Louisiana in [July](https://www.inaturalist.org/observations/88161996). Another has been observed on Quercus imbricaria in Pennsylvania in [August](https://www.inaturalist.org/observations/91046748) and on Quercus falcata in Arkansas in [August](https://www.inaturalist.org/observations/93211953).

This species was named from a wasp collected without an associated gall or host plant. Its host plants are first listed in Krombein 1951, but it's not clear when these relationships were determined or where, if anywhere, a description of the galls was published before that. The brief description in Weld 1959 is the only one available, to our knowledge. 

One or a pair of small, globular galls bursting out of splits on the lower side of leaf midribs on Quercus rubra in Boston, Massachusetts. When the galls first appear in August-September, they are light colored, but darken to red and nearly black over time. They are almost perfectly spherical in shape and tethered to the midrib by a pedicel-like structure. Their texture is slightly bumpy but hairless. The splits they emerge from are small and subtle compared to the bulges formed by species like Callirhytis piperoides or Dryocosmus deciduus on similar hosts in the fall. 

This may be a Zopheroteras, possibly [Z hubbardi](https://www.gallformers.org/gall/576). 

[The "type" observation](https://www.inaturalist.org/observations/55849213)
[The same gall a week later](https://www.inaturalist.org/observations/57326691)

Other observations made nearby:
[1](https://www.inaturalist.org/observations/59904346)
[2](https://www.inaturalist.org/observations/62053776)
[3](https://www.inaturalist.org/observations/57326608)

Similar galls on Quercus rubra have also been reported from [Newton, Massachusetts](https://bugguide.net/node/view/1149316), [Michigan](https://www.inaturalist.org/observations/61116188) [2](https://www.inaturalist.org/observations/62159776), [Ontario](https://www.inaturalist.org/observations/67687075), [Pennsylvania](https://www.inaturalist.org/observations/61978209), [Connecticut](https://www.inaturalist.org/observations/63175020), [Illinois](https://www.inaturalist.org/observations/63123015), and [Ohio](https://www.inaturalist.org/observations/60663222) [2](https://www.inaturalist.org/observations/60663392) [3](https://www.inaturalist.org/observations/64879748) [4](https://www.inaturalist.org/observations/65078060) [5](https://www.inaturalist.org/observations/65078188) [6](https://www.inaturalist.org/observations/64876762) [7](https://www.inaturalist.org/observations/64791501) [8](https://www.inaturalist.org/observations/63336366)

Fuzzy bead galls in numbers on the upper and lower sides of Sideroxylon lanuginosum leaves in Texas. They appear in April and persist throughout the season, and in later months the pubescence wears off to reveal the irregular globular shape of the galls. The inside of each gall is filled with dense erineum. Emergence holes in the fall are caused by parasitoid wasps, not the eriophyid mites that induce the galls. 

A similar gall, differing only in its white color, was [observed in Ohio](https://www.inaturalist.org/observations/58440581) in September.

White spangle galls scattered on the lower side of a Quercus muehlenbergii leaf. The galls are distinctly wider at the top and bottom than in the middle, and have a slight nipple projecting away from the leaf. The upper disk is rimmed with red. Likely Phylloteras. 

Observed in Ohio in [July](https://www.inaturalist.org/observations/87603287) and [September](https://www.inaturalist.org/observations/58359277).

Observed in Ohio in [July](https://www.inaturalist.org/observations/88593333) [(2)](https://www.inaturalist.org/observations/88592325) and [September](https://www.inaturalist.org/observations/59129225).

Clusters of several near-spherical galls emerging from the lower (or occasionally upper) midrib of Quercus montana in September and October in [Pennsylvania](https://www.inaturalist.org/observations/58859683). They differ from Andricus dimorphus in their uniform pubescence and regular spherical shape lacking a blunt, hairless outer face. They tend to occur in smaller numbers and sparser arrangements but can also be found in clusters of more than 20. They are initially white but often become longitudinally streaked with pink, sometimes more pink than white later in the season. They drop in late September and October, leaving small, round scars on the midrib. 

Similar galls have been observed in [North Carolina](https://www.inaturalist.org/observations/4193897), [Virginia](https://www.inaturalist.org/observations/61696729), [Tennessee](https://www.inaturalist.org/observations/62808729), [Ohio](https://www.inaturalist.org/observations/61617852), and possibly [DC](https://www.inaturalist.org/observations/32226871).  A similar gall has been observed on Quercus muehlenbergii in Ohio in [August](https://www.inaturalist.org/observations/55619615) and [September](https://www.inaturalist.org/observations/59701742). 

Galls matching this description have been observed on Quercus alba in September and October in Virginia.

A similar gall was [observed on](https://www.inaturalist.org/observations/138754256) Quercus margaretiae in October in North Carolina.

A gall similar to A weldi but lacking tubercles or wrinkles has been observed in October in [Virginia](https://www.inaturalist.org/observations/63127995). This may represent a distinct species, an inquiline-induced variation, or some normal range of phenotypic diversity within A weldi. 

A pair of globular greenish-tan galls found on the petiole of Quercus alba in October in [Virginia](https://www.inaturalist.org/observations/63128000). The galls were covered in short, straight, white hairs. The larger of the pair had a ring of red tissue at its apex. 

Small, tan, oblong galls scattered along the lower (occasionally upper) midrib or major side veins of Quercus velutina, phellos, and imbricaria in clusters that are initially loose but become densely packed. The galls appear tan-yellow  darkening to deep red but are densely covered in short, straight white hairs sometimes tinged with brown. They emerge from their veins in late September, but unlike Callirhytis piperoides, they emerge without causing noticeable swelling or patches of dead tissue. Their hairs are also much shorter than those of C piperoides. 

Observed in September and October in Virginia on Quercus X [leana](https://www.inaturalist.org/observations/58767226) [2](https://www.inaturalist.org/observations/62360221) (imbricaria X velutina), [phellos](https://www.inaturalist.org/observations/60447569), [velutina](https://www.inaturalist.org/observations/60757154) [2](https://www.inaturalist.org/observations/60757153) [3](https://www.inaturalist.org/observations/62360222) [4](https://www.inaturalist.org/observations/62327453), [5](https://www.inaturalist.org/observations/62327455), [6](https://www.inaturalist.org/observations/60876274), and [marilandica](https://www.inaturalist.org/observations/61155442); in Ohio on Quercus [velutina](https://www.inaturalist.org/observations/60626899) [2](https://www.inaturalist.org/observations/60662951), in Virginia on [Quercus falcata](https://www.inaturalist.org/observations/99253236), and in Michigan on Quercus [velutina](https://www.inaturalist.org/observations/60479588). A possibly similar gall was seen in [Missouri](https://www.inaturalist.org/observations/34657278). Another was seen on Quercus nigra in Arkansas in [October](https://www.inaturalist.org/observations/98000374).

Emerging leaves of Fraxinus spp. in the spring are often seen to be abruptly divided into dozens of narrow, deformed leaflets, some of which may be extremely narrow. This phenomenon often affects one leaf of an opposing pair and not the other, or may even begin halfway along the length of an otherwise normal leaf. In other cases, even the petioles and twigs are affected, causing extremely dense clusters of abortive tissue.

This symptom is often attributed to [Aceria fraxiniflora](https://www.gallformers.org/gall/658), which affects flowers on the same hosts. However, according to Amrine, Aceria fraxiniflora is distinguished from its European counterpart Aceria fraxinivora by the lack of leaf damage. It's possible this exclusion was mistaken, or that Aceria fraxinivora is responsible for these leaf symptoms (the mite has been found in North America, though [its leaf galls in Europe](https://bladmineerders.nl/parasites/animalia/arthropoda/acari/actinotrichida/prostigmata/eleutherengona/eriophyoidea/eriophyidae/eriophyinae/acerini/aceria/aceria-fraxinivora/) don't resemble the symptom discussed here). Likely the cause is something entirely different and yet to be discovered--possibly fasciation induced by mutations within the tree itself. For the moment, many observations can be found in [this observation set](https://www.inaturalist.org/observations?verifiable=any&place_id=any&field:Undescribed%20ash%20leaf%20bunching%20gall=yes) on iNaturalist. 

The case that Callirhytis glandulus and [Andricus incertus](https://www.gallformers.org/gall/927) are distinct galls formed by different species of wasps is relatively weak, based on the absence of positive evidence. The gall was originally named and described by Riley from a variety of white-group oaks on the basis of the similarity of the galls, with the variation observed attributed to differences in the anatomy of the host acorns. Beutenmuller gave the name Callirhytis glandulus to a wasp he found ovipositing in young acorns on Q prinoides. The association with the gall was never confirmed. Weld later reared a wasp from the galls now named Andricus incertus on Q bicolor, and since his wasp differed substantially from Beutenmuller's, he named it a new species, Andricus fimbriatus (note that given the alternation of generations in cynipids, the wasp ovipositing is often anatomically quite different from the wasp emerging from the gall, so it's not clear why Weld would have expected these to match even if they were the same species). Regardless, Weld cited minor differences in gall morphology and relegated the rest of "Callirhytis glandulus" to a dubious status awaiting confirmation by adult rearing as either his A fimbriatus, Beutenmuller's C glandulus, or a new wasp. Andricus fimbriatus was later found to be synonymous with another wasp captured "in buds of Q bicolor" by Bassett, Andricus incertus, an older name that took precedence over Weld's. 

The case that [Callirhytis glandulus](https://www.gallformers.org/gall/985) and Andricus incertus are distinct galls formed by different species of wasps is relatively weak, based on the absence of positive evidence. The gall was originally named and described by Riley from a variety of white-group oaks on the basis of the similarity of the galls, with the variation observed attributed to differences in the anatomy of the host acorns. Beutenmuller gave the name Callirhytis glandulus to a wasp he found ovipositing in young acorns on Q prinoides. The association with the gall was never confirmed. Weld later reared a wasp from the galls now named Andricus incertus on Q bicolor, and since his wasp differed substantially from Beutenmuller's, he named it a new species, Andricus fimbriatus (note that given the alternation of generations in cynipids, the wasp ovipositing is often anatomically quite different from the wasp emerging from the gall, so it's not clear why Weld would have expected these to match even if they were the same species). Regardless, Weld cited minor differences in gall morphology and relegated the rest of "Callirhytis glandulus" to a dubious status awaiting confirmation by adult rearing as either his A fimbriatus, Beutenmuller's C glandulus, or a new wasp. Andricus fimbriatus was later found to be synonymous with another wasp captured "in buds of Q bicolor" by Bassett, Andricus incertus, an older name that took precedence over Weld's. 

Galls matching Weld's photo were seen in April in [Louisiana](https://www.inaturalist.org/observations/74550108).

Early in the season, before they develop their characteristic sulcate appearance, C capsularis strongly resembles C acuminata and is frequently mistaken for it. Gagne states that C acuminata is absent in Texas, so observations there are almost certainly C capsularis. However, in Louisiana through Georgia and Florida, both species occur, and to be safe, IDs should be made only after the ridges are visible. 

Sources provided for this species are missing the original descriptions of Phytophaga painteri (see Gagne 2013 for citation).

All sources are listed except those pertaining to Phytophaga texana before it was moved to Celticecis in 1983. See Gagne 2014 for citations. 

C spiniformis, especially in its early growth phases, is most likely to be confused with C subulata, C conica, and C aciculata. C spiniformis is strongly flared at the base and tapering evenly to its point, larger than 3 mm, and not 5 times longer than wide. 

C conica is easily mistaken for C spiniformis, especially early in the season. C conica lacks any flaring at its base and never grows more than 3 mm tall.

C subulata can be distinguished from C spiniformis by its lack of a flared base and a height to width ratio greater than 5. 

Galls of Celticecis capsularis are commonly misidentified as C acuminata. Gagne states that only C capsularis is present in Texas (though at least two [1](https://www.inaturalist.org/observations/57874164) [2](https://www.inaturalist.org/observations/34567216) late-season galls lacking ridges have been seen there), but in areas where both occur (Louisiana through Georgia and Florida), check for incipient ridges on young galls, indicating C capsularis rather than acuminata.

Celticecis oviformis is easily identified with cross-sections but otherwise very easily confused with similar species. Gagne states that Celticecis connata is always hairless, while C oviformis is pubescent, but C connata galls with pubescence have been observed, so this may not be entirely reliable. In general, C oviformis is uniformly spherical, while C connata is irregular in size and shape and tends to be wider toward the stem than at its apex. A cross section will show a thin wall with an open interior if the gall is C oviformis, and thick, woody walls containing multiple larval cells in C connata. 

C oviformis is more difficult to distinguish from C celtiphyllia early in its development, and some observations may not be conclusively identifiable either way without a cross-section. Both galls are pubescent, often numerous and scattered across stems, petioles, and midribs, and globular with narrow nipples. As the galls develop, C celtiphyllia takes on a distinctive muffin-like shape, and the incipient swelling on the upper half of the gall can often be observed even on young galls. The interior of a C celtiphyllia gall has a bell-like shape distinct from the overall shape of the gall. 

Early in its development, Celticecis celtiphyllia can easily be confused with C oviformis, which also occurs in numbers along the stem, petiole, and midrib of the leaves, and has a similar globular form and dense pubescence. The most reliable way to confirm an ID of these two species is to take a cross-section. C oviformis has thin walls and its larval cell is the same spherical shape as the exterior of the gall. C celtiphyllia has thick walls forming a bell-shaped larval cell. As the galls develop, C celtiphyllia takes on a distinctive muffin-like shape, and the incipient swelling on the upper half of the gall can often be observed even on young galls, lacking in C oviformis. 

C celtiphyllia has also been confused with C ramicola, which also occurs along stems. C celtiphyllia can take on a somewhat ribbed appearance as it dries, but it is generally much more pubescent, near-spherical in shape, and its connection to the plant is narrow, where C ramicola attaches to the stem on a pad approximately the width of the gall. 

The arrangement along the stem and cylindrical shape of this gall are reminiscent of C ramicola, and both galls have cylindrical cells that eventually drop off the plant. C expulsa, however, grows as an integral stem gall until its capsule is mature enough to release, and leaves an empty housing for the cell when it drops, while C ramicola is a detachable gall throughout its life cycle and leaves only a pad when it falls.

A variant of this gall has been observed that lacks the high confluent base. Instead, the base of the gall attaches much lower on the detachable section and leaves a much shorter pad when the gall dehisces. See [eg this observation](https://www.inaturalist.org/observations/82148982). The source of this variation is not known and may indicate a distinct species. 

A closely related bud galler, Pachypsylla celtidisgemma, may also have white pubescence and otherwise resemble the gall of P pallida. However, this species is at most slightly pubescent, not densely woolly like P pallida. See observation and [comment here](https://www.inaturalist.org/observations/53687992#activity_comment_395f678e-77af-4d1e-905b-4b8a7586ecf0). According to Riemann 1961, this likely indicates that P pallida and celtidisgemma are endmembers of a gradient from the hairless forms in eastern Texas to the woolly forms in Arizona that could reasonably be considered a single species. 

Walshomiya cupressi

No known published resources have been located naming Hesperocyparis forbesii (Tecate cypress) as a known host, however, several examples of similar galls, not confirmed by rearing, have been observed on an isolated population of H. forbesii in San Diego, CA. 

Examples:
<a href="https://www.inaturalist.org/observations/69187202">Example 1</a>
<a href="https://www.inaturalist.org/observations/75142876">Example 2</a>

Note as well that the [2021 Gagne & Jaschhof catalog](https://www.gallformers.org/source/287) lists only "Cupressus pygmaea," a synonym for Hesperocyparis pygmaea, as a host.



Pachypsylla celtidisvesicula is the only "blister gall" caused by a named and formally described insect. Blister gall morphology varies substantially, however, and four additional species have been proposed to account for these differences. Three of these, P [reticulovesicula](https://www.gallformers.org/gall/1328), [laevovesicula](https://www.gallformers.org/gall/1327), and [rugosa](https://www.gallformers.org/gall/1329), were given formal names by Riemann 1961, but because this was a PhD thesis and not a refereed publication, the names are not valid species. 

These galls are easily distinguished from P celtidisvesicula, and less easily distinguishable from each other, by range, morphology, and host. P celtidisvesicula sensu strictu occurs in the northeastern US, from Minnesota to Quebec, north of DC; forms very small, typically numerous, galls with distinctly raised rings above, and only on Celtis occidentalis. The other three species occur primarily in Texas, with some found in Oklahoma, New Mexico, and Arizona as well, are larger and occur in smaller numbers, occasionally alone; are flat or sunken above; and are found either on Celtis laevigata, reticulata, or both.

So far, blister galls have been reported only rarely from the southeastern US. Observations from [North Carolina](https://www.inaturalist.org/observations/54967486) [(2)](https://www.inaturalist.org/observations/52384174) and [Tennessee](https://www.inaturalist.org/observations/93785670) show galls on Celtis occidentalis but lacking the distinct raised circle of celtidisvesicula and with a size and shape more similar to laevovesicula. These may be related to a fourth proposed species, listed as ["? Blister gall with upper central spine"](https://www.gallformers.org/gall/3102) by Yang 1995, noted on Celtis laevigata and tenuifolia in VA and LA, but they apparently lack the central spine, so this may be a regional variant of P celtidisvesicula or a different undescribed species. 

Nipplegall-forming psyllids on Celtis leaves are currently in a state of taxonomic uncertainty. Up to 6 species have been described from galls with distinct morphologies, all at one point synonymized as Pachypsylla celtidismamma. However, as of the most recent enumeration of species in the genus (Thomas, 2012), Pachypsylla celtidiscucurbita,  celtidisglobula, celtidismamma, and celtidispubescens were all still listed as valid. Users on Bugguide and iNaturalist have so far treated them all as synonymous, however (note that the "Pachypsylla celtidismamma complex" on Bugguide is a higher level taxon including other related psyllids, and isn't meant to distinguish the ones listed here). 

The gall of P celtidismamma sensu strictu is a round-topped nub covered sparsely in white hair and with a powdery glaucous bloom on its surface, making them resemble marshmallows. The gall typically has a slightly mushroom or muffin-like shape, with a wider round top above a narrower cylindrical base. However, this upper flaring is occasionally absent, leaving the gall more nearly a blunt cone, and shape can be irregular in other ways. No scar, nipple, or protrusion occurs at the tip; rarely there is a slight depression. Its color is green-yellow darkening to pink or purple. Hair is considered a definitional trait of this species relative to its cousins, but some are occasionally found with both their hairs and glaucous bloom apparently polished away leaving a shining surface on the upper section of the gall. The depressions each gall makes on the upper side of the leaf are shallow and unrimmed, unlike many of their close relatives.

Small tufts of long white hairs scattered in numbers between the veins of Tilia americana, more or less symmetrically on both sides of the leaf. They have been observed in [Florida](https://www.inaturalist.org/observations/77311227#activity_comment_3338efb4-2224-45d1-b903-5e830b2396f7) in May and in [Ohio](https://www.inaturalist.org/observations/29783620) in July. Old galls observed in Minnesota in October. The inducer is a midge. 

Round patches of raised or domed bark scattered along the trunk of a hackberry tree. Emergence holes suggest that either the inducing organism (or at least its parasitoids) are insects. Observed in May in [Texas](https://www.inaturalist.org/observations/77178654), though emergence holes indicate that the active season of the inducer was earlier. 

Because of their size, the galls of this generation may be difficult to see. Verifiable visual resources have not yet been established. 

Galls of Neuroterus quercusbatatus on Quercus alba and Quercus bicolor are fairly distinct, especially in the agamic generation. On Quercus alba, they seem to primarily affect the twigs of the new growing shoots in spring, swelling them into thick, elongated tuber-like swellings with glaucous surfaces, often purple in color later in the season, typically sprouting unaffected petioles and leaves. In the winter, these galls are found without leaves, often pecked open by birds to reveal the densely packed cells inside. 

On hosts other than Quercus bicolor, because both agamic and sexual generation galls occur primarily on "stems," the two generations can be somewhat difficult to distinguish when no longer fresh. Fortunately this is not necessary for a species-level ID. Beutenmuller's illustrations are not labelled to distinguish the generations so all 8 are included in both pages. 

A gall matching potentially matching this description was observed in [Ohio](https://www.inaturalist.org/observations/61309148) in September. 

Verifiable visual resources have not yet been established. 

Melikaiella flora

A gall matching the description of this species has been frequently observed on trees identified as Shreve oak, Quercus parvula var shrevei, which is known to hybridize with its known hosts. However, this relationship has not been confirmed by rearing to our knowledge.

Verifiable visual resources have not yet been established.

This species was declared a synonym of Pachypsylla celtidismamma by Tuthill and others and has been treated as such by users on Bugguide and iNaturalist. However, it is listed as valid in Thomas 2012, apparently the most recent listing of species in the genera.

Of all the debated synonyms of P celtidismamma, this species seems to resemble it most closely. Galls apparently conforming to this description have been observed in [AZ](https://www.inaturalist.org/observations/28962020) [2](https://www.inaturalist.org/observations/28962030) and [NM](https://www.inaturalist.org/observations/12551549) [2](https://www.inaturalist.org/observations/56700268) have definitely raised upper cups and are apparently smaller and longer-haired than P celtidismamma in the northern and eastern US, but differ most obviously in their range. 

This species was declared a synonym of Pachypsylla celtidismamma by Tuthill and others and has been treated as such by users on Bugguide and iNaturalist. However, it is listed as valid in Thomas 2012, apparently the most recent listing of species in the genera, and its gall is readily distinguished from Pachypsylla celtidismamma sensu strictu.

Pachypsylla celtidisglobula galls are narrow near the leaf but expand to a blunt, wide tip that resembles the bottom of a particularly squat apple in the way it pulls in to a central scar. This scar is the most reliable way to distinguish it from Pachypsylla celtidismamma sensu strictu. However, when the latter is hairless and its glaucous coat is rubbed off, it tends to be shiny, while celtidisglobula galls are never glacous and generally matte. The galls are green-apple green in the summer, fading to tan-brown by the fall or sometimes blush red-purple on the outer face. Two galls occasionally grow together, forcing each to bend at an angle. 

It is not clear how to distinguish them from P celtidiscucurbita.

This species was declared a synonym of Pachypsylla celtidismamma by Tuthill and others and has been treated as such by users on Bugguide and iNaturalist. However, it is listed as valid in Thomas 2012, apparently the most recent listing of species in the genera.

This species is labelled undescribed because the name was proposed in Riemann's 1961 dissertation, which is not considered taxonomically legitimate because it was never officially published. The species has never been formally described since. 

All observations of this species are currently ID'd as Pachypsylla celtidisvesicula on iNaturalist. However, galls tentatively identified as this species are collected in the Gallformers Code field set, see link below. The majority of blister galls observed in Texas seem to belong to this species. 

This species is labelled undescribed because the name was proposed in Riemann's 1961 dissertation, which is not considered taxonomically legitimate because it was never officially published. The species has never been formally described since. 

All observations of this species are currently ID'd as Pachypsylla celtidisvesicula on iNaturalist. However, galls tentatively identified as this species are collected in the Gallformers Code field set, see link below. All blister gall observations on Celtis in Arizona are currently assumed to belong to this species. 

This species is labelled undescribed because the name was proposed in Riemann's 1961 dissertation, which is not considered taxonomically legitimate because it was never officially published. The species has never been formally described since. 

All observations of this species are currently ID'd as Pachypsylla celtidisvesicula on iNaturalist. However, galls tentatively identified as this species are collected in the Gallformers Code field set, see link below. 

Clusters of 2-4 star-shaped galls on the buds of Quercus rubra in spring. Each gall had 6-7 flat yellow wings sweeping up to a slightly curled point tinged with red. The galls were uneven crusted with a red material but otherwise hairless and smooth. Observed in [NY](https://www.inaturalist.org/observations/77658003) in May. 

Small bead galls between the veins on the upper (occasionally lower) side of Liquidambar styraciflua leaves. They strongly resemble the galls induced by Vasates quadripedes on Acer rubrum, and are likely to be confused with that species by those unable to distinguish the hosts. The host record on Acer rubrum reported in Felt and repeated on ScaleNet seems likely to be a mistake. 

Gallformers ID Notes