Callirhytis infuscata (agamic)

Callirhytis piperoides (agamic)

Callirhytis lanata (agamic)

Neuroterus laurifoliae (agamic)

Disholcaspis bassetti (agamic)

Disholcaspis quercusmamma (agamic)

Kokkocynips decidua (agamic)

Andricus robustus (agamic)

Amphibolips confluenta

Callirhytis gemmiformis (agamic)

Amphibolips globulus (agamic)

Aceria elongata

Amphibolips trizonata (sexgen)

Feron clarkei (sexgen)

Callirhytis tubicola (agamic)

Amphibolips quercusinanis (sexgen)

Amphibolips spinosa (agamic)

Dryocosmus floridensis (agamic)

Callirhytis glandulus (agamic)

Celticecis capsularis

Celticecis celtiphyllia

Celticecis pubescens

Celticecis semenrumicis

Celticecis spiniformis

Celticecis wellsi

Neuroterus bassettii (sexgen)

Aceria celtis

Agromyza deserta

Pachypsylla celtidisgemma

Pachypsylla celtidismamma

Pachypsylla venusta

Pachypsylla celtidisumbilicus

Pachypsylla celtidisasterisca

Pachypsylla celtidisvesicula

Celticecis expulsa

Pachypsylla celtidiscucurbita

Pachypsylla celtidispubescens

Pachypsylla celtidisglobula

Phylloteras rubinum (agamic)

Amphibolips quercusfuliginosa (agamic)

Amphibolips niger (agamic)

Amphibolips tinctoriae (agamic)

Amphibolips nubilipennis (sexgen)

Amphibolips quercusracemaria (sexgen)

Amphibolips acuminata (sexgen)

Amphibolips quercusspongifica (sexgen)

Amphibolips quercuscinerea

Amphibolips melanocera (sexgen)

Amphibolips quercuscitriformis

Amphibolips ilicifoliae (sexgen)

Amphibolips cookii (agamic)

Amphibolips quercusostensackenii (sexgen)

Amphibolips quercuscoelebs (sexgen)

Dryocosmus cinereae (sexgen)

Macrodiplosis majalis

Diastrophus turgidus

Neuroterus clarkeae (sexgen)

Amphibolips femoratus (sexgen)

Neuroterus niger (agamic)

Cecidomyia hageni

Xylotrechus aceris

Synanthedon acerni

Dasineura communis

Anthocoptes transitionalis

Vasates quadripedes

Acericecis ocellaris

Dasineura rileyana

Dasineura aceris

Vasates aceriscrumena

Aculus minutissimus

Aceria major

Aculus quinquilobus

Eriophyes aceris

Aceria modesta

Rhyncaphytoptus magnificus

Aceria spicati

Aceria calaceris

Contarinia negundinis

Contarinia a-negundo-bead-gall

Aceria negundi

Neuroterus pallidus (sexgen)

Callirhytis exigua (sexgen)

Andricus wheeleri (agamic)

Aceria dina

Phylloxerina nyssae

Aceria nyssae

Unknown n-sylvatica-twig-swelling

Heteroecus chrysolepidis (agamic)

Dasineura meibomiae

Rhopalomyia erigerontis

Phylloxera perniciosa

Aceria vaga

Caryadiplosis biconvexa

Caryomyia tubicola

Caryomyia subulata

Caryomyia stellata

Caryomyia ansericollum

Caryomyia sanguinolenta

Phylloxera caryaesepta

Phylloxera caryaesepta (perforans)

Andricus infuscatus 

Globular, fleshy, monothalamous leaf gall with dense, yellow wool, diameter 5 to 6 mm, on upper surface, on Q catesbaei [laevis].

Andricus piperoides

Clustered, pubescent, globular, drab or brownish red midvein galls, frequently splitting and extending along the vein 4 to 8 cm, diameter 3 to 9 mm, occur in clusters of 10 to 100 or more on a leaf, on Q rubra. 

Dryophanta lanata

Bunches of pale brown wool on under surface of leaf, each with 2 to 8 triangular or irregularly conical cells, diameter 5 to 15 mm, on Q rubra, coccinea, velutina, marilandica, phellos, nana [ilicifolia]. 

Neuroterus laurifoliae

Globose, kernel-like leaf galls occurring singly or in clusters and covered with long, loose, fawn-colored wool, diameter of kernel 2 to 2.5 mm, on Q laurifolia, Q imbricaria.

Disholcaspis bassetti

Globose, usually with a produced, curved apex, single or clustered twig gall, green turning to brown, on Q platanoides [bicolor], Q imbricaria [mistake--likely confused with Callirhytis ventricosa].

Disholcaspis mamma

Globose, obscurely pointed, green, bright red, turning to brown or dark red, diameter 6 to 18 mm, on Q platanoides [bicolor] Q macrocarpa. 

Andricus decidua

Rounded or elongate midrib swellings filled with oblong or elongate kernels, a few to 40; when young concealed in the tissues and bursting open in October, on Q rubra, Q velutina.

Cynips vacciniiformis

Globose, clustered, monothalamous, midrib gall with a more or less distinct nipple apically and a long stem basally, brown when old, probably green when fresh, diameter 4 to 7 mm, stem i to 2.5 mm, resembles a huckleberry, on post oak.

Amphibolips confluens

Oak apples, intervening substance is spongy, size large

Globular, smooth, shining or opaque leaf gall, internally a juicy, white, spongy substance and a large central larval cell, green, turning with age to light brown, diameter 2.5 to 5 cm, usually on a vein or petiole, on Q rubra, coccinea, and velutina in May and June.

Andricus gemmiformis

Bud-shaped, elongate, pointed apically, thin-walled and hollow. Length 3 to 4 mm, on trunk of white oak.

Amphibolips globulus

Globular, thick-shelled, slightly nippled twig gall, green, becoming brown, diameter 14-17 mm, on Q marilandica.

Eriophyes elongatus
[Eriophyes maculatus, regulus, Phyllocoptes constrictus and variabilis are also listed as distinct valid species causing the same symptom. Only elongatus is now understood to be a valid inducer; the others are synonyms, vagrants, or inquilines.]

Acer saccharum

Red erineum on the upper leaf surface


Amphibolips trizonata Ashm.

Galls of the aments or catkins
Globose, moderately thick-shelled, yellowish, almost smooth, pithy gall, diameter 20 to 33 mm, possibly on oak blossoms. 

Dryophanta clarkei

Gall consisting of one or more larval cells or capsules in a leaf bud
Capsules in the bud, blasting it completely or so that only a few deformed and imperfect leaves appear
Polythalamous, small, round, brown, thin-walled bud gall, diameter 3 mm, on Q alba, Q minor [stellata], resembles gall of D vesiculus [[Neuroterus vesicula]](https://www.gallformers.org/gall/840).

Andricus tubicola

Galls composed apparently of crystalline matter; attached to the leaves
Clustered, tubular

Spined oak tube gall. Tubular leaf gall, length 7 to 10 mm, narrow basally, open apically, yellowish, the surface with numerous red spines, the interior divided by two horizontal partitions, the basal and distal cavities empty, the latter open, on Q obtusiloba [stellata].

Amphibolips inanis

Oak apples, i.e. galls with a central, hard kernel or larval cell, a firm (often hard) outer shell, and a spongy or fibrous intervening substance, The substance lying between the rind and the kernel is fibrous and often very scanty; Size large, kernel central, leaf usually aborted

Globose, bright green, becoming yellowish brown, slightly nippled, thin-shelled glossy leaf gall, the central larval cell supported by radiating fibers, diameter 25 to 35 mm, on Q coccinea, rubra in May and June.

Amphibolips spinosa

Spiny oak apple. Globose, spined, brown, thick-shelled leaf gall, internally slightly spongy, diameter 7.5 mm, on Q laurifolia. 

Dryophanta floridensis

Gall consisting of one or more larval cells or capsules in a leaf bud
Cells surrounded by a rosette of linear leaves

Dormant bud galls covered with short fuzzy abortive leaflets and occurring in clumps on trunks of Spanish oak (Q digitata [falcata]) and blue jack oak (Q brevifolia [incana]).

Andricus glandulus

Irregular, monothalamous, conical swellings of the cupule, length 5 mm, diameter 2 mm, on Q platanoides [bicolor], macrocarpa, prinoides, and prinus [montana]

Cecidomyia capsularis

Rosette-shaped, ribbed leaf gall resembling the seed capsule of Hibiscus, on under surface of leaf, diameter 2 to 3 mm.

Phytophaga celtiphyllia

Conical, flask-shaped or subglobular, slightly ribbed, greenish leaf or tender twig gall arising from a circular, truncate base, diameter 3-4 mm. 

Cecidomyia pubescens 

Leaf gall resembling that of Pachypsylla pubescens but with no cup-chaped depression on the upper surface of the leaf, diameter 3.5 to 4 mm.

Cecidomyia semenrumicis

Twig galls resembling seed capsules of Rumex, apically with a spine about one-half the length of the gall, the height, excluding the spine, 4.5 mm, the diameter approximately the same.

Cecidomyia spiniformis 

Conical, spine-shaped leaf gall on the under surface and arising from a circular, yellowish base, height 4 mm, diameter 2.8 mm. 

Cecidomyia unguicula

Subconical leaf gall, clustered on the under surface, length 3 to 5 mm.

Phytophaga wellsi

Top-shaped, monothalamous, moderately thick leaf gall, the surface sparsely clothed with whitish, appressed pubescence, the greatest diameter 3 to 4 mm.

Neuroterus pallipes

[this species occurs twice, in different places in the key]

Galls of the leaves (in some cases the leaf itself is aborted and the gall issues from the twig or bud)
Gall a swelling of the midvein or sometimes of the petiole
Less abrupt and localized enlargements of midveins (more rarely of lateral veins and the petiole)
Oval, thin-walled, monothalamous vein swellings covered with a dense, brown pubescence, on Q alba

Small, thin-walled, globose or fusiform galls, usually marginal, on the leaf and piercing the lamina
Oval, thin-walled, monothalamous vein swellings covered with a dense, brown pubescence, on Q alba

Eriophyes sp.

"Witch-broom" on branches and twigs

Cecidomyia deserta

Hollow, elongate twig swellings, length 1.25 to 2.5 cm.

Pachypsylla gemmaria

Bud-shaped, polythalamous twig gall without an opening.

Pachypsylla mamma

Mammiform, very large leaf gall without a depression or rim on the top, usually not pubescent, sometimes with a slight down at the base, diameter 4.5 mm.

Pachypsylla rohweri

Elevated, mammiform, with a long nipple-like protuberance, diameter 6 mm, on under surface of leaf of C reticulata.

Pachypsylla venusta

Reniform, large, petiole gall involving the base of the leaf and with an opening, polythalamous.

Pachypsylla umbilicus

Circular, depressed leaf gall on the upper surface, the outer rim depressed, the central part slightly raised and with a median spine; wartlike on the under surface, much flattened and with a depression in the middle; height 2 mm, diameter 5 mm.

Pachypsylla asteriscus

Star-shaped or flower-shaped leaf gall and not forming a depression on the under side, on the upper surface blisterlike, height 1.25 mm, diameter 5 mm.

Pachypsylla vesiculum

Blisterlike, yellowish, monothalamous gall occurring on both sides of the leaf and hardly raised above the surface.

Cecidomyia sp.

Subconical, solitary or compound leaf, stem, petiole or fruit gall with a bluntly truncate, dehiscent larval cell, diameter about 4 mm.

Pachypsylla cucurbita

Globose, not pubescent, sessile leaf gall, wider than high, much flattened on the top and usually with two concentric, elevated rims and a central nipple.

Pachypsylla pubescens

Subglobular, sessile, smaller leaf gall with long hairs and with a smooth, shining impression on the upper surface, diameter 3 mm.

Pachypsylla globulus

Globular, subsessile, small leaf gall with a small impression at the top, not pubescent.

Biorhiza rubina

Globose, rosy, juicy leaf galls on the upper surface, diameter 2 to 3 mm, on Q alba.

Amphibolips fuliginosa

Globose, smooth, corky, reddish brown twig or acorn gall, with a large central cell, diameter 8 to 12 mm, on Q laurifolia.

Globose, small, red, smooth, corky, probably acorn galls, diameter 8 to 12 mm, on Q laurifolia.

[Felt reproduces Beutenmuller's figures]

Amphibolips nigra

Globose, densely woolly, peach-like twig gall. Diameter 22 to 50 mm.

Amphibolips tinctoriae

Almond-shaped, pointed, keeled bud or twig gall, green or reddish, becoming brown, smooth, rather thick-shelled with a central, fiber-supported cell, length 12-20 mm, on Q velutina and rubra in autumn.

Amphibolips nubilipennis

Globular or ovate, green, sometimes tinged with pink, succulent, translucent leaf gall, diameter 6 to 18 mm, on Q rubra and coccinea.

Amphibolips racemaria

Globose, crisp, sour and succulent, green, becoming brown, leaf gall, internally with a reddish larval cell, diameter 8 to 10 mm, on Q laurifolia in April and May.

Amphibolips acuminata

Fusiform, tapering, the apex usually somewhat curved, yellowish brown twig gall, internally spongy, with a hard larval cell, length 3 to 5.5 cm, diameter 1.5 to 3 cm, on Q marilandica in May and June.

Amphibolips longicornis

Globose, monothalamous, very thin-shelled leaf and twig gall, internally soft, light, spongy, not unlike A confluens form spongifica, diameters 3.5 and 3 cm.

Amphibolips carolinensis

Globular leaf gall resembling that of A confluens form spongifica, and A cinerea, but the surface is more coarsely reticulated and less glossy and the larval cell much darker in color, diameter 2.5 cm, on midrib near base of leaf, on Q ?minor

Amphibolips cinerea

Globose or ovate, slightly nippled, dark, crimson with lighter mottlings and becoming brown, thick-shelled twig gall with filament-supported larval cell, length 2.5 to 3.5 cm, diameter 2 to 3 cm, on Q brevifolia [incana].

Amphibolips melanocera

Globose or ovate, yellowish green or brown, glossy when dry, thin-shelled, slightly nippled, axillary bud gall, diameter 7 to 15 mm, on Q nigra.

Amphibolips citriformis

Fusiform to subglobular, pointed, yellowish, thin-shelled twig gall with a fiber-supported cell, length 12 to 24 mm, diameter 6 to 12 mm, on Q phellos.

Amphibolips ilicifoliae

Elongate, fusiform, dark green leaf gall, usually arising from the petiole, internally an ovate, fiber-supported cell, length 25 to 55 mm, diameter 7 to 20 mm, on the upper leaf surface of Q nana [ilicifolia].

Amphibolips cookii

Globose, slightly nippled, green, spotted with red, becoming brown, moderately thick-shelled twig or bud gall, with a fiber-supported, central cell, diameter 16 to 18 mm, on Q rubra in September and October.

Andricus singularis

Globular, smooth, green leaf gall, diameter 6 to 12 mm, on red oak.

Amphibolips coelebs

Elongate or fusiform, pointed leaf or twig gall, usually with a long pedicel, the prolongation of a leaf vein, pale green, thin-shelled and with an oblong, thin larval cell supported by radiating fibers, length 20 to 25 mm, diameter 4 to 8 mm, on Q coccinea and rubra.

Dryophanta cinereae

Subglobose, greenish gray, somewhat longitudinally ribbed, rugose, sessile galls; internally, with a loose kernal, diameter 4 mm, height 3.25 mm, on Q cinerea [incana]

Cecidomyia quercus majalis

Pod-shaped oak apple. Gall of same type as Cecidomyia niveipila but more thin-walled and bladder-like and never tomentose.

Massachussets. June.

Diastrophus turgidus

Rubus strigosus

Mass. Over winters. All around stem.

Neuroterus clarkeae

Light brown, budlike, thin-shelled, marginal leaf gall covered with short wool, length 2 to 3 mm, on Q alba.

Andricus femoratus

Globular, very thin-shelled leaf gall containing a fiber-supported cell, diameter 8 mm, on Q laurifolia.

Neuroterus niger

Globose or blisterlike, monothalamous leaf vein swellings more distinct on the upper side and with a minute nipple on the lower surface, diameter 1 to 1.75 mm, on Q. alba and Q. macrocarpa. 

[Felt reproduces Beutenmuller's drawing]

Itonid. Cecidomyia hageni Aldr. Small, woolly capsule on under surface of the leaf, on A. macrophylla

Xylotrechus aceris

Acer rubrum

Irregular twig swellings resembling those on willow and poplar made by Saperda concolor.

Sesia acerni

Acer rubrum

Irregular, oval, roughened branch swellings, length 10 to 15 cm, diameter 6 to 10 cm.

Dasyneura communis

Acer rubrum

Pouch vein galls, greenish or reddish, length 6 mm.

Acer saccharum

Thickened vein galls, green to brownish, length 3 to 5 mm.

Anthocoptes transitionalis

Acer rubrum

Pustular areas in the smooth bark of red maple.

Phyllocoptes quadripes

Acer rubrum, saccharinum

Small bladder like greenish or reddish leaf galls, diameter 2.5 mm, very abundant, on the upper surface.

Cecidomyia ocellaris

Acer rubrum

Ocellate, yellow, red-margined blister leaf gall, diameter 3 to 4 mm.

Rhabdophaga rileyana

Acer rubrum

Irregular leaf folds, summer

Dasyneura sp.

Acer rubrum

Distorted, rolled leaves bearing cocoons, possibly identical with the preceding [Dasineura rileyana]. Summer.

Rhabdophaga aceris

Acer saccharinum

Free larvae on irregularly curved leaves.

Phyllocoptes aceris-crumena

Acer rubrum, saccharinum [sic--this seems to be mistaken compared to later literature]

Slender, fusiform leaf galls, length 5 mm. Sometimes very abundant, on the upper surface, also on sugar maple [Acer saccharum] and white-barked maple [Acer leucoderme].

Acer saccharum, leucoderme

Slender, fusiform leaf galls, length 5 mm. Sometimes very abundant, on the upper surface, also on soft maple [Acer saccharinum--sic] and white-barked maple [Acer leucoderme].

Phyllocoptes minutissimus

Acer rubrum

Red erineum on the upper leaf surface

Eriophyes sp. [these two species are presumably also A minutissimus]

Acer rubrum

A whitish or brown erineum in elongated patches on the veins, on the upper side of the leaf.

A whitish, frostlike erineum with small spots of rosy pink spreading broadly along the main veins, on the upper surface.

Eriophyes major
Eriophyes ornatus [listed as two distinct species causing the same symptom; quinquilobus is also listed]

Acer rubrum

Pinkish erineum on the under leaf surface

Eriophyes sp. [this is, presumably, the same species as well?]

Acer rubrum

Yellowish to deep brown erineum in large patches on under side of leaf.

Phyllocoptes quinquilobus
[Eriophyes major and ornatus are also listed as two distinct species causing the same symptom]

Acer rubrum

Pinkish erineum on the under leaf surface

Eriophyes sp.

Acer saccharinum

A pale yellow to deep brown erineum on the under side of the leaf.

Eriophyes modestus

Acer saccharum

Greenish erineum on the under leaf surface

Eriophyes sp. [these three are presumably also A modesta]

Acer saccharum

A white or whitish erineum in patches on the under side of the leaf

A rusty or brown erineum on the under leaf surface, forming patches along the veins.

Acer leucoderme

An erineum in scattered patches, mostly on the under surface of the leaf and slightly dimpled.

Phyllocoptes magnificus

Acer platanoides

Epidermal, hairy growths in vein axils, on the under leaf surface.

Eriophyes parallelus

Acer spicatum

Whitish erineum on the upper [sic] leaf surface

Eriophyes sp.

Acer glabrum

A purple erineum in large patches at the tips of the lobes and on the upper side of the leaf, sometimes sprinkled over the under side.

Cecidomyia negundinis

Acer negundo

Terminal bud galls with a diameter of 1 to 2 cm or greatly swollen, deformed leaflets, the thickened midrib forming a mass 3 cm long and 7 mm in diameter, the blade being almost aborted.

Contarinia negundifolia [this specific name is now listed as a synonym of Contarinia negundinis, but the gall Felt describes here matches this leaf gall]

Acer negundo

Variable, subglobose leaf gall, diameter about 2 mm.

Eriophyes negundi
Phyllocoptes splendidus

Acer negundo

 A white erineum or shallow dimple on the under side of the leaf, sometimes involving entire leaves of young or basal shoots

Eriophyes sp.

Acer negundo

Warty swellings on the leaves. 

Neuroterus pallidus

Globose, monothalamous, pale wood colored galls in dense clusters near the ends of the aments, on Q platanoides [bicolor]

Andricus exiguus

Oval, small, short, dark slate colored, ament galls, length 1.25 mm, diameter 1 mm, on Q obtusiloba [stellata]

Andricus wheeleri 

Irregularly rounded or elongate, somewhat potato-shaped, polythalamous oak twig gall, length 15 to 30 mm, diameter 14 to 20 mm, on unknown scrub oak.  Beutm. '07, p. 464


Eriophyes sp.

Nyssa

A narrow infolding of the leaf margin upon the upper surface, dark brown when dry, elegantly scalloped.

Cecidomyia nyssaecola

Nyssa

Marginal leaf fold, length 2.5 to 3.5 mm

Eriophyes nyssae

Nyssa

Small, round capsule gall on the leaf, often lobed above, conical below, with an opening at the apex

Cecidomyia sp.

host: Nyssa

Twig gall, length 4 to 5 cm, diameter 8 mm.

Andricus chrysolepidis

Ovate or globular, nippled, presumably twig gall containing a larval cell and covered with a dense, fine, short, pubescence, diameter 5 to 8 mm, on Q chrysolepis.

Dasyneura meibomiae

Elongate, fusiform, clustered bud gall, length 8 to 22 mm.

Rhopalomyia erigerontis

Host: Erigeron fragilis [foliosus]

Oval apical bud gall, length 10 mm, diameter 7 mm.

Phylloxera perniciosa

Carya

Leaf folds and ridges
Globular or irregular, terminating in a toothlike nipple and occurring on tender twigs, petioles or ribs of leaves, often confluent, smooth, diameter 2 to 8 mm. 

Petiole or twig galls
Globular or irregular, terminating in a toothlike nipple and occurring on tender twigs, petioles or ribs of leaves, often confluent, smooth, diameter 2 to 8 mm. 

Eriophyes sp.

Carya sp.
Axillary vein galls
Small, axillary galls in the angles of the lateral veins.

Cecidomyia sp.

Carya sp.
Leaf blisters
Irregular, dull greenish or black-margined, slightly nippled, diameter 3 mm.

Caryomyia tubicola

Carya sp.
Cylindric leaf galls
Greenish or black, cylindric, length 4 to 5 mm, diameter 1 mm. 

Cecidomyia sp.

Carya sp.
Cylindric leaf galls
Similar to [preceding](https://www.gallformers.org/gall/553) but longer, curved and tapering, length 5 to 7 mm, diameter 1.4 mm, light green basally, dark brown or black apically.

Cecidomyia sp.

Carya sp.
Cylindrical leaf galls
Slender, tapering, suberect, light greenish with flaring, dentate base, length 5 to 8 mm, basal diameter 2.5 to 3.5 mm.

Caryomyia caryaecola [assignment to C ansericollum based on Gagne]

Carya sp.
Conical leaf galls, without a distinct orifice
Base subglobular, a long, slender apical process, greenish to reddish brown, length 3 to 4 mm, occurs in groups on midrib of bitternut hickory. [Felt lists two photos associated with this gall, one of which appears to resemble Caryomyia supina and the other caryomyia stellata. Neither match Felt's written description]

Caryomyia sanguinolenta

Carya sp.
Conical leaf galls, without a distinct orifice
Conical, nearly symmetrical, thin-walled, small, green or red tinted, length 2 mm.

Phylloxera caryaeseptem

Carya sp.
Conical or globose leaf galls with distinct orifice and containing aphids
Galls more or less conical above and beneath, opening on the upper surface, both nipples surrounded at the apex by a fringe of long filaments, walls thin, more or less transparent, diameter 5 to 12 mm, height 4 to 6 mm.

Phylloxera caryaeseptem var perforans

Carya sp.
Conical or globose leaf galls with distinct orifice and containing aphids
Similar to the [preceding](https://www.gallformers.org/gall/2876), with both cones very much elongated, slender and toothlike, length of cones 3 to 8 mm, diameter 2 to 4 mm.

Key to American Insect Galls