Phylloxera notabilis

Phylloxera caryaeavellana

Phylloxera caryaecaulis

Phylloxera spinosa

Phylloxera caryaemagna

Phylloxera subelliptica

Phylloxera caryaefallax

Phylloxera caryaefoliae

Phylloxera caryaeglobuli

Phylloxera caryaegummosa

Phylloxera caryaeren

Phylloxera caryaescissa

Phylloxera caryaesemen

Phylloxera caryaesepta

Phylloxera caryaesepta (perforans)

Phylloxera caryaevenae

Phylloxera castaneae

Phylloxera conica

Phylloxera deplanata

Phylloxera depressa

Phylloxera devastatrix

Phylloxera foveata

Phylloxera foveola

Phylloxera georgiana

Phylloxera globosa

Phylloxera intermedia

Phylloxera minima

Phylloxera perniciosa

Phylloxera picta

Phylloxera pilosula

Phylloxera querceti

Phylloxera reticulata

Phylloxera davidsoni

Phylloxera rileyi

Phylloxera rimosalis

Phylloxera russellae

Phylloxera spinuloides

Phylloxera stellata

Phylloxera symmetrica

Phylloxera texana

Phylloxera tuberculifera

Phylloxerina nyssae

Phylloxera glabra

Stegophylla quercina

Thecabius affinis

Thecabius gravicornis

Thecabius populimonilis

Thecabius lysimachiae

Pachypappa pseudobyrsa

Pachypappa rosettei

Pachypappa sacculi

Pemphigus betae

Pemphigus bursarius

Pemphigus knowltoni

Pemphigus longicornis

Pemphigus monophagus

Pemphigus nortonii

Pemphigus obesinymphae

Pemphigus populicaulis

Pemphigus populiglobuli

Pemphigus populitransversus

Pemphigus populivenae

Pemphigus tartareus

Pemphigus populiramulorum

Thecabius populiconduplifolius

Cornaphis populi

Eriosoma rileyi

Georgiaphis ulmi

Georgiaphis gillettei

Tetraneura ulmi

Eriosoma americanum

Eriosoma grossulariae

Eriosoma lanigerum (on-ulmus)

Eriosoma lanigerum (on-malus)

Eriosoma mimicum

Eriosoma pyricola

Tetraneura akinire

Kaltenbachiella ulmifusa

Colopha ulmicola

Prociphilus caryae (on-amelanchier)

Phylloxera notabilis Pergande   

Galls on leaves of Carya illinoiensis are ovoid to spherical, bladder-like, very variable in size (diameter 2-18 mm), situated close to mid-rib, projecting on both sides of leaf, green on top with a central nipple, and reddish-green beneath covered with dense short yellowish hairs.  Alatae emerge from the top of the gall, which generally splits into long slender bract-like segments in June-July.  There is no host alternation. Several generations of galls are produced each year; the smaller, secondary galls occurring mainly on seedling trees (Stoetzel & Tedders 1981).  Brachypterous and migratory alatae, sexuparae and sexuales are all produced in the primary galls.  Sexuales lay overwintering eggs on bark (Whitehead & Eastep 1937).  In eastern and southern USA.  Andersen & Mizell (1987) studied the physiological effects of galling on the host. Calcote (1983) studied resistance of pecan clones to P. notabilis. Medina et al. (2011) demonstrated that populations identified as P. notabilis collected from water hickory (C. aquatica) in east Texas always lacked two species of symbiotic bacteria that were present in populations on pecan. There were also found to be distinct differences in DNA (AFLP) profiles, and in host preferences and performance of alatae in reciprocal transfers between the two Carya species (Dickey & Medina 2010, 2011), all of which indicate that the phylloxerid on water hickory is a different, presumably undescribed, species.

Phylloxera caryaeavellana Riley   

Galls projecting underneath leaf are globular, pale greenish, like a small hazelnut (5-10 mm diam.), above leaf flat or slightly concave.  Galls mature in May-June, emergent alatae have orange abdomen, BL 0.9-1.2 mm (Pergande 1904).  On Carya tomentosa in Washington, D.C.  The life cycle is unknown.

Phylloxera caryaecaulis (Fitch)  

Galls are on young twigs, on petioles or at bases of leaflet main veins, sometimes in clusters; globular, diam. 5-25 mm, pale yellowish green tinted with red before opening, afterwards becoming leathery and black.  Typically on Carya glabra in eastern USA.  There is no host alternation.  

Shimer (1869) described three other closely-related phylloxerid species producing somewhat different twig or petiole galls on other species of Carya, which may or may not be synonymous with P. caryaecaulis: P. spinosa, producing galls covered with fleshy spines on Carya sp, in Illinois; P. caryaemagna, producing velvety galls on petioles or at base of mid-rib on C. amara (= cordiformis) in Illinois and Missouri; and P. subelliptica, producing ellipsoid mottled green galls on side of twig of C. alba (= ovata) in Illinois (see also Pergande 1904).  

Phylloxera caryaecaulis (Fitch)  

Shimer (1869) described three other closely-related phylloxerid species producing somewhat different twig or petiole galls on other species of Carya, which may or may not be synonymous with P. caryaecaulis: P. spinosa, producing galls covered with fleshy spines on Carya sp, in Illinois.

Phylloxera caryaecaulis (Fitch)

Shimer (1869) described three other closely-related phylloxerid species producing somewhat different twig or petiole galls on other species of Carya, which may or may not be synonymous with P. caryaecaulis: P. caryaemagna, producing velvety galls on petioles or at base of mid-rib on C. amara (= cordiformis) in Illinois and Missouri

Phylloxera caryaecaulis (Fitch)

Shimer (1869) described three other closely-related phylloxerid species producing somewhat different twig or petiole galls on other species of Carya, which may or may not be synonymous with P. caryaecaulis: P. subelliptica, producing ellipsoid mottled green galls on side of twig of C. alba (= ovata) in Illinois (see also Pergande 1904).  

Phylloxera caryaefallax Riley   

Galls on leaves of Carya alba (= ovata) are thin-walled, 1-5 mm diam., on upper side of leaf and convex with a central nipple-like opening below leaf.  Alatae with dark-veined wings and orange-yellow abdomen, BL 2.3-2.8 mm, emerge in May-early June (Pergande 1904).  In Missouri, Illinois and states bordering the Mississippi at least as far south as Tenessee.  The life cycle is unknown.  

Phylloxera caryaefoliae Fitch   

Galls on leaves of Carya glabra project above leaf as pale green slender cones with pale rings at their bases, c. 5 mm diam., almost flat on underside of leaf with a central nipple.  Alatae emerge from the upper side of the gall (Pergande 1904) in early June.  In north-eastern USA (New York, Illinois, Iowa, Virginia).  The life cycle is unknown. 

Phylloxera caryaeglobuli Walsh   

Galls according to original description are spherical, on leaf lamina between veins, opening in June to release alatae through a simple longitudinal slit on underside of leaf.  On shagbark hickory (= Carya ovata) in Illinois and Missouri.  Pergande (1904) recorded the available information, and suggested that P. hemispherica Shimer might be a synonym.  The life cycle is unknown.

Phylloxera caryaegummosa Riley   

Galls are spindle-shaped, suspended from the underside of leaf of Carya alba (= ovata) by a slender petiole; they are white or yellowish, pubescent and sticky.  In Illinois and Missouri, USA.  Alatae are undescribed and the life cycle is unknown.

Phylloxera caryaeren Riley   

Galls develop in clusters along leaf petioles and mid-ribs of leaflets of Carya glabra; they are reniform, pale green, 2-15 mm max. diam., placed transversely to axis of petiole, deeply divided by a transverse slit and opening into two halves (rather like a bivalve mollusc) when mature (Pergande 1904). The phylloxerid itself is still undescribed, and the life cycle is unknown.  In Illinois and Missouri, USA.

Phylloxera caryaescissa Riley   

Galls are globular, diam. 8-14 mm, pale greenish or dirty yellowish green, clothed with short fine yellowish hairs, projecting about eqally on both sides of leaf lamina, opening underneath when mature (mid-May to mid-June) by a transverse slit (Pergande 1904). On Carya tomentosa in eastern USA (Florida, D.C.).  The life cycle is unknown.

Phylloxera caryaesemen Walsh   

Galls are rounded, small (diam. 0.3-2.0 mm) and very numerous, yellowish green to brownish yellow, rather tough and leathery, projecting more above leaf than below, with a more-or-less depressed centre above and opening (in July-early August) by a central nipple-like opening underneath. On Carya glabra in Illinois and Missouri, USA; Shimer (1869) also recorded it from C. amara (= cordiformis) in Illinois. 

Phylloxera caryaesepta (Shimer)  

Galls of Carya alba (= ovata) have conical projections both above and below leaf, with nipple-like apices fringed with filaments when mature, the structure on both sides of the leaf somewhat resembling a miniature sea-anemone (diam. 5-12 mm).  Colour of gall varies from pale yellowish green to red.  Alatae emerge in late May-June from upper side of gall (Pergande 1904).  In Illinois and Missouri, USA.  On Carya glabra further east (New York, Virginia), the same or a closely-related species forms galls with a narrower conical structure above and below leaf (P. caryaesepta var. perforans; Pergande 1904).  The life cycle is unknown.

Phylloxera caryaevenae Fitch   

Galls on Carya tomentosa and several other Carya spp. are distinctive, usually pale yellowish green, elongate folds along the main veins on the underside of the leaflet, with corresponding ridges or carinae above.  The opening is a slit on the underside.  There is no host alternation.  Galls are mostly dry and empty by mid-August, but no alatae are known; the sexuales are produced from late July by apterous sexuparae in free-living colonies in deep bark fissures on the trunk and branches (Pergande 1904).  Widely distributed in eastern USA, from New York to Florida and as far west as Illinois and Missouri.

Phylloxera castaneae (Haldeman)  

Apterae are pale yellow, BL c. 1 mm, on both sides of leaves, especially along the mid-ribs, of Castanea spp. (dentata, mollissima, pumila, sativa) in north-eastern USA (New York, Maryland, D.C., West Virginia).  Infested leaves become much distorted and desiccated.  Stoetzel (1985b) demonstrated host alternation in West Virginia from galls on Carya tomentosa.  The galls and gall generations have not yet been described; the galls are similar to those of P. intermedia (M.B. Stoetzel, pers. comm.).  Alatae from these galls gave rise to large populations on Castanea spp., causing yellow discoloration along the leaf veins. Pergande (1904) drew attention to the fact that most of the immatures on the upper sides of the chestnut leaves were bright orange (as opposed to pale yellow), and had longer tubercles than those on the undersides; his name spinifera is available for this form should it prove to be specifically distinct.

Phylloxera conica (Shimer)  

Galls are almost globular, projecting on both sides of the leaf, diameter 3-7 mm in plane of leaf, deep purplish brown, with a roughened or granular surface texture, becoming pubescent and covered with a sticky secretion when mature.  Alatae emerge when the gall splits open underneath in June, and presumably fly to an unknown secondary host.  Originally described from Carya alba (= ovata) in Illinois, USA (Shimer 1869), but the description above is of galls on C, amara (= cordiformis) in Missouri identified as this species by Pergande (1904).  Riley (1875) suggested synonymy with P. depressa, but this does not accord with Pergande's interpretation of the species.

Phylloxera deplanata Pergande   

Galls on leaves of Carya tomentosa are circular, diameter 1-5 mm, slightly convex above leaf and more prominent beneath, with an oval orifice fringed with fine hairs.  Their colour is reddish to yellowish or greenish yellow above leaf and purplish to dull greenish yellow beneath.  There is no host alternation; fundatrices produce sexuales in the galls in May, but some alatae may also be produced.  Galls are empty, brown and dry by late June (Pergande 1904).  Only known from D.C., USA.

Phylloxera depressa (Shimer)  

Galls on leaves of Carya alba (= ovata) in Illinois, USA are numerous, smooth, diameter 4-6 mm, convex and pale yellowish green above leaf, whiter beneath with a central nipple-like projection and a round opening.  Alatae are present in the gall in late June (Shimer 1869).  The life cycle is unknown.  According to Riley (1875), conifera Shimer is a synonym.

Phylloxera devastatrix Pergande   

Clusters of galls occur on young twigs, leaf petioles or flower stalks of Carya illinoensis in southern and south-eastern USA (Arkansas, Louisiana, Mississippi, Oklahoma, Texas), often causing serious economic damage.  The galls are globular, of irregular shape, smooth, green or yellowish green with a reddish tinge before maturity, diameter 3-15 mm.  They open in May-early June by means of a transverse split into four or more broad bracts, releasing alatae that immediately start to oviposit on neighbouring twigs, etc.  There is no host alternation. The eggs develop into dwarf sexuales that mate and lay overwintering eggs under bark or at the base of the tree.  

Phylloxera foveata (Shimer)  

Galls on leaves of Carya amara (= cordiformis)  are small (1.5-8.4 mm diam.), with a dimpled central depression above, opening beneath leaf by a rounded downy orifice.  Alatae were plentiful in late June.  In Illinois, USA (Shimer 1869).  The same leaves carried galls of P. minima and P. caryaesemen.

Phylloxera foveola Pergande   

Galls on leaves of Carya glabra in Virginia, USA are circular, yellow-green tinged with pink or red, 3-5 mm diam., convex and rather prominent above leaf with a deep central dimple or depression which is pinkish in colour, part below leaf convex or depressed with a small conical central nipple.  Alatae (BL c. 1.2 mm, with slender, orange abdomen) are mature in galls in late May and most had emerged before June, indicating that there is probably host alternation, but the secondary host is unknown.  Possibly it is a synonym of P. foveata; the emergence time was the principal reason given for separating the two (Pergande 1904), but this might vary according to weather conditions or host plant.

Phylloxera georgiana Pergande   

Galls occurred singly or in clusters on tender twigs and petioles of an unidentified Carya sp., presumably at Georgiana, Florida (Pergande 1904).  They were similar to those of Ph. devastatrix; more-or-less globular, with a short nipple, greenish yellow (sometimes reddened on one side), or wholly dark red, 5-10 mm in diameter.  Alatae (BL 0.8-1.0 mm, with orange abdomen) differ from P. devastatrix in characters of the wings and antennae (see Pergande 1904).

Phylloxera globosa (Shimer)  

Galls on leaves of Carya amara (= cordiformis) in Illinois are mostly rather large, globular and projecting equally on both sides of leaf, or conical and projecting only below leaf, with flat circle above ("form conifera"); smooth, leathery, pale yellowish green to dark green, with a small central opening below leaf surrounded by small bracts.  According to Pergande (1904), the smaller galls included in Shimer's (1867) original description were those of Ph. caryeaesemen.  Alatae emerge very late in year, in late September-October.  The life cycle is unknown.

Phylloxera intermedia Pergande   

Galls on leaves of Carya alba (= ovata) are circular, reddish or yellowish, 3-6 mm in diameter, convex to conical on upper side of leaf without any trace of a central nipple, paler and almost flat with a small closed nipple on underside.  Alatae emerge in late may-June, mainly from a jagged opening formed by splitting of the upper surface of the gall (Pergande 1904). Locality not stated; probably in vicinity of Washington, D.C. The life cycle is unknown.

Phylloxera minima (Shimer)  

Galls on Carya amara (= cordiformis) in Illinois USA are small, round (diameter 1.1-5.0 mm) and numerous, with part protruding above leaf shining brightly, and a small opening beneath.  Alatae, present in the galls in early July (Shimer 1869).  The life cycle is unknown.

Phylloxera perniciosa Pergande    

Galls on young twigs, leaf petioles and along midribs of leaflets of Carya tomentosa are elliptical, with a blunt tooth-like or thorn-like projection.  In Maryland, Virginia, D.C. and Pennsylvania; large gall populations in Virginia caused defoliation of trees (Pergande 1904).  Also reported from C. illinoensis in Louisiana and Mississippi (Carpenter et al. 1979), although the identity of these populations with Pergande's species needs confirmation.  Living all year around on Carya, with three generations per year; fundatrices, alate sexuparae and sexuales.  Alate sexuparae emerging from galls in May-early June laid eggs indiscriminately on trees and surrounding vegetation.  Sexuales laid overwintering eggs in June, mostly high in trees on twigs that had been previously galled.  The eggs were preyed upon through the summer by various natural enemies. including mites of six different genera.  Surviving eggs hatched the following April (Pergande 1904).

Phylloxera picta Pergande   

Galls on leaflets of Carya tomentosa resemble those of Ph. intermedia, but have thinner walls, adn a central nipple above as well as below the leaf; colour variable, diam. 3-6 mm.  Alatae emerge from an opening on the upper side in late May-June (Pergande 1904).  Locality not stated; probably in vicinity of Washington, D.C.  The life cycle is unknown.

Phylloxera pilosula Pergande   

Galls on leaflets of Carya glabra near Washington, D.C. are flat or with a central depression above leaf and projecting with a well-developed central nipple below leaf; diam. 3-6 mm, pale green to whitish, both sides densely covered with long, soft, glistening, yellowish white hairs.  Alatae emerge from the underside of the gall in early June (Pergande 1904).  The life cycle is unknown.

Phylloxera querceti Pergande   

On undersides of leaves of Quercus spp. (alba, dentata(?), macrocarpa) in the vicinity of Washington, D.C. (Pergande 1904), Duncan 1922).  Affected leaves are speckled with small yellow spots, especially near mid-ribs and along smaller veins. 

Phylloxera reticulata Duncan   

Apterae are bright orange-yellow, with reddish eyes; BL c. 0.8 mm.  On undersides of leaves of Quercus kelloggii in California, USA, dispersed along veins.  Only apterae are described (Duncan 1922), and they have not been recorded since.

Phylloxera davidsoni Duncan   

Apterae light orange to yellowish brown; BL c. 0.7 mm.  Immatures are pale yellow, alatae orange with black thorax.  On undersides of tomentous young leaves of Quercus engelmanni in California, USA (Duncan 1922).  The life cycle is unknown.

Phylloxera rileyi Riley   

Apterae are dark brown with dorsal tubercles almost black (but paler forms mat occur); BL c. 0.6 mm.  On undersides of leaves of Quercus alba and Q. obtusiloba (= stellata) in Missouri, causing white or yellow circular spots.  Apparently there is no host alternation; alatae are produced from late July to October, and those of later generations are presumably sexuparae, because sexuales are recorded laying overwintering eggs on twigs (Riley 1875, Pergande 1904, Duncan 1922).

Phylloxera rimosalis Pergande   

Galls on Carya tomentosa in eastern USA (Washington, D.C.) are fairly large and conspicuous (diam. 3-11 mm), pale green sometimes tinged with red, usually on terminal leaves of young shoots; flat to slightly convex above leaf, more prominently convex with a central nipple beneath.  Alatae (BL c. 1 mm, with pale orange abdomen) emerge in late May-June through a round opening on the underside (Pergande 1904).  The life cycle is unknown.

Phylloxera russellae Stoetzel   

Galls on Carya illinoensis in southern USA are circular, flattened, diam. 3.2-7.2 mm, with a reticulate surface pattern.  They project from both sides of a leaflet with an opening on the underside marked by white pubescence.  Galls mature and break open in May.  No alatae are known.  There is no host alternation; apterous sexuparae produce sexuales which develop in the gall in May and produce overwintering eggs in galls, on twigs, etc. (Stoetzel 1981).  Heavy populations of galls can cause defoliation.  Calcote (1985) studied resistance of pecan clones to P. russellae.

Phylloxera spinuloides Pergande   

Galls on petioles or at bases of main veins of leaflets, of an undetermined Carya species in Florida, USA, were globular (diam. 5-15 mm), with a dense covering of long fleshy filamentous outgrowths; usually encircling the petiole and causing it to bend or curve.  Colour uniformly greenish yellow, or brownish yellow on one side.  Galls opened in late March, releasing alatae (BL 0.6-1.8 mm, with brownish wings and orange abdomen).  Life cycle is unknown, although the early departure of alatae suggests host alternation.

Phylloxera stellata Duncan   

Apterae (BL c. 0.5 mm, colour unrecorded) caused brown spots on undersides of leaves of a Quercus sp., margaretta (= stellata or alba, in mid-August in Texas, USA (Duncan 1922). Other morphs and life cycle are unknown.

Phylloxera symmetrica Pergande   

Galls on leaves of Carya tomentosa and other Carya spp. are variable; typical form is circular and almost flat above leaf, protruding as a thick-walled pale cone below leaf, basal diam. 2-5 mm.  Alatae (BL 0.9-1.2 mm, with orange abdomen) emerge in late May-early June through a small opening in the apex of the cone, after which the galls become dry and brown.  In vicinity of Washington D.C., USA.  Life cycle is unknown.  Pergande (1904) described variants from the typical form of gall ("vasculosa" and "purpurea") differing in colour, size and shape, which he considered to be due to differences in hatching time of the fundatrices and developmental stage of the leaf at onset of feeding.

Phylloxera texana Stoetzel   

Galls on leaves of Carya illinoensis are globular, projecting mainly on upper side of leaf, with a small point below; diameter 4-6 mm (Stoetzel 1981).  Alatae (BL 1.0-1.6 mm, with golden yellow abdomen) emerge in mid to late May through a large opening in the top of the gall, which splits into bracts.  In Texas, USA.  Host-alternating; alatae from galls colonised undersides of leaves of Quercus spp. (falcata, virginiana), these colonies producing both alatae and apterae in June (Stoetzel 1985b).  The return migration to pecan has not been observed.

Phylloxera tuberculifera Duncan   

Apterae (BL c. 0.5 mm, colour unrecorded) caused brown spots on undersides of leaves of Quercus havardii in Texas, USA, in August (Duncan 1922).  Other morphs and life cycle are unknown.

Phylloxerina nyssae (Pergande)   

Galls are usually crescent-shaped, yellowish-white, formed in spring by rolling, scalloping and swelling of edges of leaves of Nyssa sylvatica (Stoetzel 1993). Later in the year (September), lemon-yellow apterae, BL 1.0-1.3 mm, completely covered in white wax wool, occur together with sexuales in bark crevices of young trees, particularly in cavities caused by dropping out of dead twigs about 2 m above ground level. Apparently there is no host alternation. In Maryland and Washington D.C., USA (Pergande 1904).

Phylloxera glabra (von Heyden) 

Living without host alternation mainly on Quercus robur.  Fundatrices feed in spring from main veins, sometimes causing inward curling of leaf-edge as in Ph. confusa.  Subsequent generations include yellowish orange apterae (BL 0.7-0.85 mm), which lay circular clusters of eggs on the underside of the leaf, and both apterous and (later) alate sexuparae (Grassi 1912).  Feeding causes necrotic spots on leaves.  In Europe (England, France, Germany, Italy), and introduced to New Zealand, where it is recorded from Q. dentata (Sunde 1984). A record from Turkey (Şenol et al. 2014c) requires additional confirmation. Anholocyclic overwintering may occur; Lubiarz (2007) observed overwintering of immature stages of P. glabra (and/or P. coccinea) in bark crevices in Poland. 

Stegophylla quercina Quednau  (= quercicola of Blackman & Eastop 1994)  

Apterae are pale yellowish-green with brown head, covered with bluish-white wax wool; BL 1.6-1.9 mm. On leaves of Quercus spp., usually of the red oak group, in dense flocculent masses which may cause curling and yellowing (Quednau, 1966). Oviparae and apterous males occur in October (the males are true apterae without a sclerotised thorax). In eastern North America. Quednau (2010) distinguished two subspecies, with S. quercina s.str. known from Quebec and New York (BMNH collection, leg. R.L. Blackman), and S. quercina acutirostris Quednau, known from Wisconsin and North Carolina. The latter subspecies makes pseudogalls on the infested Quercus spp. (Quednau 2010). 2n > 30 (for quercina s. str.).

Thecabius affinis (Kaltenbach) 

Galls occur on Populus spp., in May-June, mainly on P. nigra and its varieties, and are formed by folding of young leaves in half along mid-ribs; the outer, upper side of the leaf becomes blistered and yellowish or reddish (see [influentialpoints.com/Gallery](https://influentialpoints.com/Gallery/Thecabius_affinis_Poplar-buttercup_gall_aphid.htm)). These are secondary galls containing only the alatiform progeny of the fundatrix, which inhabits a small gall of its own formed by folding the edge of a leaf (fig. 131I). 

T. affinis occurs on a wide range of Populus spp. throughout Europe and across Asia to east Siberia, Japan and Korea, and also in North America (see below). 

COI barcode sequences have confirmed that T. affinis is present in North America (Skvarla et al. 2017). DNA data have also confirmed the existence of a separate North American species, Thecabius populiconduplifolius (Cowen), which has 2n=28 (Harper & Macdonald 1966). T. populiconduplifolius is virtually indistinguishable from T. affinis and has an identical biology, but with native poplars as primary hosts (Palmer 1952).

Thecabius (Parathecabius) gravicornis (Patch)

Galls are formed by folding leaves downward along the mid-rib to form a yellowish-green, swollen pocket which becomes filled with the developing emigrant alatae. The fundatrix inhabits a separate small pocket on the upper side of a leaf lamina (Palmer 1952). On Populus balsamifera in North America, widely distributed but apparently rather rare; also collected on P. angustifolia in Utah (BMNH collection, leg. R. Danielsson). Alatae (BL 1.7-2.8 mm, with olive-yellow abdomen) migrate in July-August, presumably to an unknown secondary host.

Thecabius populimonilis (Riley)   

The galls on Populus spp. (angustifolia, balsamifera, fremontii, trichocarpa) are rows of ovoid, bead-like cells, pale green or with a reddish tinge, developed from upper side of leaf lamina on both sides of mid-rib (see [influentialpoints.com](https://influentialpoints.com/Gallery/Thecabius_populimonilis_bead-like_cottonwood_gall_aphid.htm)). Each gall in spring contains one developing aptera or alata. The fundatrices inhabit similar, solitary galls. This species is apparently facultatively monoecious; Gillette (1913) suggested that the large alatae (BL 2.7-3.0mm) produced in individual galls in June-July might recolonize cottonwoods, but it seems more likely that they are emigrants and found colonies of apterous exules in wax on Salix roots such as those observed by Lange (1943) in California. Presumably alatae produced in these colonies in October are sexuparae and return to Populus. However, alate sexuparae (BL 1.7-2.0mm) are also produced in galls on Populus, up to 12 per gall, in August-October (Maxson & Knowlton 1929, Palmer 1952, Harper 1959a). A more recent study by Aoki et al. (1996b) has confirmed most of these observations; they found heteroecious and monoecious life cycles at different locations, but their data on sex ratios indicate that some gene flow is probably occurring, rather than that two separate species are involved. Pike et al. (2012) have also now confirmed by DNA barcoding that colonies on willow roots (probably Salix dodgeana) in Washington are T. populimonilis. This species is widely distributed in USA, western Canada and Mexico. (Pemphigus saliciradicis may be a synonym; see note under that species.)

Thecabius (Parathecabius) lysimachiae Borner  

Galls containing developing emigrant alatae are formed by folding and convoluting the leaf of Populus nigra (fig. 131J). The fundatrix inhabits a separate oval pocket-gall on the upper side of the leaf lamina, as in other Parathecabius. Alatae (BL 2.3-2.6 mm, with dark, dirty greenish abdomen) migrate in late June-July to roots and runners of Lysimachia spp., especially L. nummularia. Other species, e.g. Lysimachia (= Glaux) maritima, may also be colonised. Apterae on Lysimachia are brownish or greyish green, with wax; BL 1.1-1.8 mm. Alate sexuparae return to poplars in September, but anholocyclic overwintering on Lysimachia is also common. In Europe, North Africa (Tunisia; Boukhris-Bouhachem et al. 2007) and central Asia, and recently (2000) recorded from New York State, USA (Foottit et al. 2006). T. luppovae (Narzikulov), described from Populus densa (= P. talassica) in Tajikistan, may be a synonym. 2n=18.

Pachypappa pseudobyrsa (Walsh)  

The fundatrix is wax-dusted, yellowish olive green with a blackish head; BL 4.0-4.7 mm.  Its feeding causes a small blister-like swelling in the centre of the underside of the leaf near the mid-rib (see [influentialpoints.com/Gallery](https://influentialpoints.com/Gallery/Pachypappa_pseudobyrsa_poplar_leaf-purse_aphid.htm)).  Its numerous progeny spread out in May-July along the main veins, developing into dusky-dark alatae, BL c. 3.5 mm.  On Populus spp. (deltoides, fremontii, tremuloides) in eastern North America, where it is widely distributed, and also in Colorado (Palmer 1952, as Asiphum).  The life cycle is unknown; the alatae presumably migrate to an unknown secondary host, although Smith (1974a) thought that it might be monoecious.

Pachypappa rosettei (Maxson)  

Feeding by the fundatrix (BL 2.5-2.8 mm, appearance in life unknown) causes bending of leaves and stunting of stems to form a rosette-like nest, as in the closely-related European species P. tremulae.  On Populus tremuloides in Colorado and Utah, USA, and secondary host populations are now recorded from Washington and Alaska (Pike et al. 2012). Alatae (BL 2.2-2.5 mm) are produced in July.  Host alternation to roots of Picea spp. has now been confirmed by DNA bar-coding, and the apterous exule (BL 0.8-1.4 mm) redescribed (Pike et al. 2012). Aphids on roots of Pseudotsuga menziesii have also been tentatively assigned to P. rosettei (Danielsson 1990a). Anholocyclic overwintering may occur on spruce roots (Pike et al. 2012). Aphids infesting the roots of potted conifers in Canada and identified as P. tremulae may also be this species.

[records of Pachypappa tremulae, a European species are likely attributable to P rosettei:] The numerous records from North America on roots of Picea spp. and Pseudotsuga menziesii (also as Asiphum tremulae and Rhizomaria piceae; Lavallee 1987) may all be due to confusion with P. rosettei (Footit et al. 2006).

Pachypappa sacculi (Gillette)  

The fundatrix is wax-dusted, slate grey with brown head; BL 4.5-5.0 mm.  It forms a large bag-like gall on P. tremuloides, with edges and tip of leaf curled downward (Harper 1966; as Asiphum).  In western USA (Arizona, Colorado, Utah, Washingtom, Alaska) and across Canada (British Columbia, Alberta, Quebec, Ontario and Nova Scotia).  Progeny of the fundatrix are all alate, with dark olive-green abdomen, BL 3-4 mm.  Host alternation to Picea spp. has now been confirmed by DNA bar-coding, and a redescription provided of the apterous exule (BL 0.9-1.8 mm) (Pike et al. 2012). Anholocyclic overwintering may occur on spruce roots (Pike et al. 2012). 2n=10.

Pemphigus betae Doane (= balsamiferae Williams)  

Galls are yellowish green sometimes tinged with red, pocket-like, formed usually on the underside of the poplar leaf near its base, on or adjacent to the mid-rib, with little or no deformation of the leaf (Harper 1959a, Whitham 1978).  The opening can be either on the upper side of the leaf or underneath along the mid-rib.  Primary hosts are Populus angustifolia, P. balsamifera, or occasionally P. deltoides ssp. occidentalis or P. trichocarpa.  Alatae (BL 1.5-2.1 mm) leave galls in late June-early August (Harper 1959b), to colonise roots of Beta vulgaris, and also perhaps on other Amaranthaceae (formerly Chenopodiaceae) such as Chenopodium album, and possibly Spinacia.  Apterae on chenopods are yellowish aphids secreting white wax, with BL 1.9-2.4 mm. Anholocyclic populations can persist all year on secondary hosts (see Moran & Whitham 1988), and are widely distributed in North America. The life cycle was studied by Harper (1963) in southern Alberta, and by Moran & Whitham (1988) in Utah.  This aphid's evolutionary ecology has been studied in some detail, including the territorial behaviour of first instar fundatrices in selection of galling sites (Whitham 1979), population dynamics in relation to galling site (Whitham 1978, 1980), genetics of resistance in the host plant (Paige & Capman 1993), induction of sexuparae (Moran et al. 1993a), and discrimination between host trees by returning sexuparae in autumn (Moran & Whitham 1990).  However, interpretation of all this work is problematic as Foottit et al. (2010a) have demonstrated that there is a complex of Pemphigus species in western North America  sharing the same cottonwood primary hosts. Taxonomic affinities with palaearctic populations of Pemphigus on chenopod roots (see P. fuscicornis) are unclear. See also Blackman & Eastop (2000).

Pemphigus bursarius (Linnaeus)  Poplar‑Lettuce Aphid,  Lettuce Root Aphid     

Galls on Populus spp. (most commonly P. nigra) are yellowish or reddish when mature, purse-shaped, always formed on leaf petioles (fig. 131L, and see [influentialpoints.com/Gallery](https://influentialpoints.com/Gallery/Pemphigus_bursarius_Poplar-lettuce_gall_aphid.htm)).  The fundatrix is greyish green, slightly wax-dusted.  Alatae (BL 1.6-2.5 mm) leave the gall through a lateral opening over an extended period from late May to September, with peak emergence in late June-July (northern hemisphere). They found colonies mainly on roots of Compositae/Asteraceae (e.g. Cichorium, Lactuca, Lampsana, Sonchus, Taraxacum, Tussilago). Many of the records of P. bursarius from roots of plants in other families may be referable to other Pemphigus spp. Return migration of sexuparae to poplar is in October-September, but anholocyclic overwintering on roots of secondary hosts is common. P. bursarius occurs in Europe, across Asia to eastern Siberia (Babichev & Kirichenko 2020), northern and southern Africa, North and South America, and (perhaps) Australia and New Zealand. There is some uncertainty about its occurrence in Australia and New Zealand because, although  bursarius-like aphids occur in bursarius-type galls on Populus and are also recorded from Sonchus roots, the secondary host populations are mainly recorded from Amaranthaceae and Polygonaceae. Miller et al.. (2005) found genetically distinct populations on different secondary host plants, indicating a complex of races and/or subspecies. Dunn (1960a) studied gall formation and (1960b) reviewed natural enemies.  Alleyne & Morrison (1978a, b) gave accounts of its biology and natural enemies in Quebec. See also Blackman & Eastop (2000).  2n=20.

Pemphigus knowltoni Stroyan   

Galls are green, pouch-like, of variable shape, on undersides of leaves of Populus angustifolia alongside the mid-rib at the base of the lamina (Stroyan 1970).  Fundatrix and immatures in gall are blackish green.  Alatae (BL 1.8-2.1 mm) are mature in the gall in July, and migrate to an unknown secondary host.  Described from Utah, USA. 

Pemphigus longicornus Maxson   

Galls are elongate, thin-walled, on upper sides of leaves of Populus deltoides.  The fundatrix is pale yellowish white.  Alatae (BL 1.7-2.1 mm) emerge in May-June and migrate to an unknown secondary host (Maxson 1923).  In eastern and southern USA.  [According to Smith (1985), there is also an undescribed Pemphigus sp. on P. deltoides in North Carolina that causes elongate to slightly globular galls on the upper sides of the leaves, and has alatae with antennae intermediate in length and antennal sensoriation between longicornus and populivenae.]

Pemphigus monophagus Maxson  

The gall is globular, pale greenish yellow, consisting of a swelling of upper side of base of leaf lamina with petiole broadened and somewhat twisted, and a slit-shaped opening underneath between petiole and leaf (fig. 131N, and Maxson 1934).  Fundatrix honey-yellow to pale olive-green, producing a generation of creamy white apterae in the gall.  Monoecious, alatae (BL 1.4-1.9 mm) emerging from galls in August-September to deposit sexuales on the bark of the trunk.  On Populus angustifolia, P. balsamifera and P.trichocarpa in western North America.  Aoki & Kurosu (1988) discussed the evolution of monoecy in this species.

Pemphigus nortonii Maxson  

Galls on Populus deltoides especially var. occidentalis (= monilifera) are pale yellowish green, formed by a swelling at the base of the leaf lamina, twisted on the flattened, broadened petiole; resembling those of P. populicaulis (Palmer 1952), but with a long slit-like opening (Harper 1959a).  Alatae emerge over an extended period (June-Sept; Harper 1959b, Grigorick & Lange 1968), migrating to an unknown secondary host.  Apparently widely distributed in USA, and in Alberta, Canada.  Apart from the greater number of rhinaria on ANT V and VI this species closely resembles P. junctisensoriatus.  Populations from Alberta (Harper 1959a, b) seem to be intermediate in this respect, and the distinction between these two species needs to be verified.

Pemphigus obesinymphae Aoki & Moran  

Galls are formed on the petioles of late flushing leaves of Populus fremontii (Aoki & Moran 1994), and P. deltoides (Abbot 2009), usually close to the leaf blade. When mature they are almost spherical, 8-16 mm in diameter, with the lips of the transverse slit sometimes bulging outwards, and a circular ostiole about 1.2 mm in diameter somewhere along the slit. First instar progeny of the fundatrix in the gall are heavily sclerotised with well-developed fore legs and attack predators (Moran 1993). Abbott (2009) demonstrated using microsatellite DNA analysis that there was a high level of clonal admixture within galls, and Grogan et al. (2010) investigated its consequences. Alatae (BL 1.9-2.5 mm) fly in August-October, presumably migrating like P. populitransversus to cruciferous hosts (N. Chen et al. 2009), on which overwintering occurs. Sexuparae return to Populus in May of the following year, and the eggs hatch only a short time after oviposition. Apparently widely distributed in USA (Ohio, Tennessee, Arizona, Utah, Texas), and probably in northern Mexico. N. Chen et al. (2009) recorded molecular and phenological differences between P. obesinymphae and P. populitransversus on cabbage in Texas. This species was confused for many years with P. populitransversus (q.v.), and its distribution and range of both primary and secondary hosts requires further confirmation.

Pemphigus populicaulis Fitch   

The gall is yellowish green to creamy, formed by swelling of base of leaf lamina, twisted around broadened petiole, rather like that of P. nortonii and P. populiglobuli but with a small, rounded exit hole on the underside (Palmer 1952, Harper 1959a).  Especially associated with P. deltoides and P. deltoides ssp. occidentalis (= monilifera), but also recorded from other cottonwoods and P. tremuloides.  The fundatrix is pale yellowish to whitish green.  Alatae (BL 1.7-2.0 mm) emerge in July-September.  The secondary host has not definitely been established; Glendenning (1924) reported that it was Oenanthe sarmentosa, but did not provide evidence for this assertion.  Hottes & Frison (1931) suggested that P. brevicornis Hart, described from corn roots, was the sexupara of populicaulis.  Widely distributed in North America.  Setzer (1985) studied gall mortality.  Sokal et al. (1980) and Bird et al. (1982) studied geographical variation in eastern North America using multivariate techniques.

Pemphigus populiglobuli Fitch   

The gall is green, often tinged with red and/or yellow when mature; globular, conical or bullet-shaped, formed by swelling of base of leaf lamina and thickening of petiole, the exit hole being a slit on the underside between leaf and petiole (Maxson & Knowlton 1929).  Primary hosts are Populus angustifolia and P. balsamifera, more rarely P. trichocarpa.  The fundatrix is variously reported to be dark green (Palmer 1952) or pale yellowish white (Maxson & Knowlton 1934).  Alatae (BL 1.5-2.3 mm) leave gall in June-early July (Alberta; Harper 1959b) for an unknown secondary host.  Widely distributed in North America.  Differences from P. populicaulis and other closely-related species are discussed by Maxson & Knowlton (1929).

Pemphigus populitransversus Riley 

The gall is formed by swelling and bending of petioles of the leaves of Populus deltoides (incl. ssp. occidentalis) and P. fremontii; it is green, globular to ovoid, with a usually transverse slit (see [influentialpoints.com/Gallery](https://influentialpoints.com/Gallery/Pemphigus_populitransversus_poplar_petiole_gall_aphid.htm)).  Sometimes recorded from other Populus spp. (acuminata, angustifolia, balsamifera, nigra, tremuloides, trichocarpa)  However, some of these records, particularly those from western cottonwoods, may apply to other species.  The fundatrix is whitish to pale dirty greenish yellow (Palmer 1952).  Alatae (BL 1.7-2.0 mm) emerge in July and found colonies of pale yellow aphids in flocculent wax on roots of Brassicaceae (Jones & Gillette 1918), where it can be a serious pest (Royer & Edelson 1991).  Sexuparae return to cottonwood in September-October to produce sexuales which lay overwintering eggs on the bark. Geographic variation in eastern USA has been studied extensively using multivariate methods (Sokal & Riska 1981).  Bingham & Sokal (1986) studied host tree effects on morphology.  P. populitransversus is recorded throughout most of North America east of the Rocky Mountains. However it is still unclear whether the name is being applied to a single species; apart from the confusion with P. obesinymphae (q.v.), Bird et al. (1979) found that two forms with different gall shape and phenology, and corresponding morphological differences in fundatrices and emigrant alatae, occur sympatrically on P. deltoides over a large area of the USA east of the continental divide. It should be noted that the morphology of their aphids from globular galls on late flushing leaves does not correspond with that described for P. obesinymphae.

Pemphigus identified as P. populitransversus have been found on Populus sp. in Mexico (BMNH collection, leg. R. Peña) and Chile (BMNH collection, leg. G. Monsalve); it has also been introduced to South Africa (Müller & Scholl 1958), where it occurs on Populus nigra (BMNH collection, leg. E McC. Callan) and P. deltoides, and the Azores (on Populus sp.; BMNH collection, leg. A. van Harten).  Presumed anholocyclic populations also occur in New Zealand on Eutrema wasabi roots (BMNH collection, leg. L.M. Emms), and aphids collected on Arabis roots in England (BMNH collection, leg. G. Fox-Wilson) may also be this species.  2n=20.

Pemphigus populivenae Fitch   

Galls are elongate pocket-shaped or cock's comb-shaped, greenish or yellowish or pale red, arising alongside mid-rib on upper side of leaf, with a slit-shaped opening underneath.  On heavily-infested trees, galls may occur on both sides of the leaf, and those on the underside may then be confused with those of P. betae (Maxson & Knowlton 1934; however see also Footit et al. 2010). Whitham (1978) reported that P. populivenae galling Populus fremontii in Utah caused chlorosis of the leaf distal to the gall. As in the case of P. betae, several species of cottonwoods and their hybrids are colonised (angustifolia, balsamifera, deltoides, fremontii and trichocarpa; the latter species in experimental conditions only).  The fundatrix is yellowish green.  Alatae (BL 1.1-1.8 mm) emerge in June-July and migrate to found colonies on roots of Amaranthaceae.  Rumex (Polygonaceae) may also be colonised. The evidence for this host alternation is work in California by Grigorick & Lange (1962), who transferred sexuparae from sugar beet to poplar bark under controlled conditions and obtained fundatrices that produced galls specifically on P. trichocarpa.  The alatae from these galls were identified as P. populivenae, and colonised roots of B. vulgaris and Chenopodium album.  However, the suggested synonymy of both P. betae and P. balsamiferae with populivenae indicates some confusion of identity, and further work seems advisable to confirm that the correct name for populations damaging sugar beet in California (e.g. Summers & Newton 1989) is in fact populivenae rather than betae.  Foottit et al. (2010) have found molecular evidence that at least three taxa with similar galls occur sympatrically on cottonwoods in Alberta. 

Pemphigus tartareus Hottes & Frison  

(= Pemphigus junctisensoriatus Maxson)   

Described originally from alate sexuparae collected on roots of Bidens sp. in Illinois, USA. Galls on Populus deltoides are pale yellowish green, composed mostly of swollen leaf petiole around broadened base of leaf lamina, with an exit hole in the form of a long slit between the petiole and the leaf (Maxson 1934).  The fundatrix is pale yellowish white, with brownish head and tibiae. Alatae (BL 1.4-1.8 mm) emerge in June-July and migrate to Bidens sp(p). Smith (1985) established the synonymy with P. junctisensoriatus and made successful host transfers from Populus to Dichondra repens (Convolvulaceae) as well as to Bidens.  In USA and eastern Canada.

Pemphigus populiramulorum Riley   

Galls are formed by swelling of new growth of twigs, or rarely at the bases of petioles; they are quite large (up to 2.5 cm diam.), rounded, green to brownish, with a transverse or vertical slit-shaped opening which often has protruding lips.  The primary host is usually Populus deltoides ssp. occidentalis (= monilifera), but it is also recorded from P. balsamifera and P. fremontii.  The fundatrix is pale creamy yellow (Palmer 1952).  Alatae (BL 2.2-2.5 mm) leave galls in July-September (Harper 1959b), flying to an unknown secondary host.  In western North America (Utah, Colorado, South Dakota).

Cornaphis populi Gillette   

Galls on Populus angustifolia are crescent-shaped folds of the leaf-edge, pale or streaked with red.  In western USA (Wyoming, Colorado, Utah).  Apterae inhabit the same galls as the slate-grey fundatrices, and are straw-yellow with black head and four dark patches on the pronotum, dusted with wax.  There is no host alternation; alate sexuparae (BL 2.0-2.3 mm) are produced in the galls in July (Gillette 1913, Palmer 1952).

Eriosoma rileyi Thomas   

On bark of trunk and branches of small elms (Ulmus americana, rubra) in North America, forming small colonies covered with wax wool very like those of E. lanigerum on apple, and causing similar deformation of woody tissue.  It lives all-year-round on elm, without forming leaf-galls.  Apterae under the wax are pinkish, yellow or brown; BL 1.8-2.3 mm.  Alatae produced in June to August have ANT III 0.8-1.0 × head width across (and including) eyes, with secondary rhinaria rather widely spaced.  Sexuparae are apterous, produced in September-October, depositing dwarf sexuales directly onto bark (Patch 1913, Palmer 1952). 

Georgiaphis ulmi (Wilson)  

Gall is formed by curling one edge of the elm leaf into a spindle shape, 2-5 cm long.  Galled leaves turn yellow, then red, then drop off (Wilson 1911).  Fundatrix reddish-brown.  Monoecious holocyclic, and apparently specific to Ulmus alata.  Alate sexuparae, reddish brown with black head and thorax, are produced in second generation (Wilson 1911), leaving galls in May-June.  In eastern North America.

Georgiaphis gillettei Maxson & Hottes   

Forms leaf-curl galls on Ulmus americana and U. fulva (for illustration see Hottes & Frison 1931, as G. ulmi).  Fundatrix and apterous fundatrigeniae are greenish blue, dusted with wax.  Monoecious holocyclic on Ulmus.  Alate sexuparae maturing in galls in June are greenish brown to greenish blue, wax-dusted; BL c. 1.5-1.6 mm) (Maxson & Hottes 1926).  In eastern North America (Illinois, Iowa, North Carolina, Pennsylvania; BMNH collection).  Synonymised with G. ulmi by Hottes & Frison (1931), but reinstated as a distinct species by Smith (1985).  G. gillettei has R IV+V equal to or longer than HT II, whereas G. ulmi has R IV+V distinctly shorter than HT II.

Tetraneura ulmi (L.)  Elm‑Grass Root Aphid   

Galls are stalked, approximately bean-shaped (fig. 134D), smooth and shiny, reddish-green and/or yellow (see [influentialpoints.com/Gallery](https://influentialpoints.com/Gallery/Tetraneura_ulmi_Elm-grass_root_aphid.htm)), on leaves of various Ulmus spp. (campestris, glabra, minor). Their histology was investigated by Álvarez et al. (2013). Urban (2003a) made a detailed study of its bionomics on elms. T. ulmi occurs commonly in Europe, across Asia to eastern Siberia (Pashchenko 1988a) and northern Japan, and was introduced to North America. Alatae (BL 1.8-2.6 mm) (fig. 117E) emerge in June-July to colonize roots of Poaceae. Apterae on grass roots (Plate 1d) are pale orange yellow, yellowish white or reddish, with head, prothorax, and appendages brown; the body lightly dusted with wax; BL 1.7-2.8 mm. They are found on numerous species of Poaceae (especially Agropyron, Bromus, Dactylis, Deschampsia, Festuca, Holcus, Hordeum, Lolium, Poa, Zea), are invariably ant‑attended, and often in ants' nests. Overwintering occurs commonly on grass roots or in ants' nests,  root‑feeding colonies producing rather few sexuparae in autumn. Ivens et al. (2012a,b) used microsatellite DNA analysis to investigate clonal diversity of root-feeding populations in the Netherlands. Zwölfer (1957) made a detailed study of root-feeding populations, including comparison with the closely related and perhaps synonymous Tetraneura longisetosa (Dahl), collected from roots of Brachypodium, Deschampsia and Festuca in Germany. Tetraneura chui Zhang, described from Sorghum vulgare (= bicolor) in China, may also be a synonym. 2n (T. ulmi) =14 (gall generation); Galli & Manicardi reported 2n =14 to 16.

Eriosoma americanum (Riley)  

Spring colonies on Ulmus americana roll the edges of the leaves downwards (see [influentialpoints.com/Gallery](https://influentialpoints.com/Gallery/Eriosoma_americanum_woolly_elm_aphid.htm)).  Emigrant alatae (fig.118C) emerging from galls in June are dark green to blue-black with some wax wool, and rather dark wing veins; BL 2.0-2.5 mm.  They migrate to form colonies of pale pink, woolly apterae on roots of Amelanchier.  Return migrants to elm in August to October produce dwarf sexuales that lay overwintering eggs on bark (Patch 1915a, Palmer 1952).  It occurs throughout the natural range of U. americana in eastern North America, and in the west on planted elms.

Eriosoma (Schizoneura) grossulariae (Schüle)   

Forming open, green to yellow curled-leaf galls on Ulmus spp. (fig. 134L), similar to those of E. ulmi, with which this species was confused for many years (see Danielsson 1982).  Immature alatae in galls are light green (cf. ulmi), maturing in June; dark green when adult, migrating to found colonies on roots of Ribes sanguineum and R. uvacrispa.  Apterous exules are pale red to yellowish white in white wax wool; BL 1.0-2.3 mm. Alate sexuparae in autumn bluish grey to black, with secondary rhinaria distributed III 15-24, IV 2-5. Throughout Europe, Japan, and also introduced on European elms into North America.  2n=10.

Eriosoma lanigerum (Hausmann)  Woolly Apple Aphid   

Apterae on Pyroideae are purple, red or brown, covered with thick white flocculent wax (see [influentialpoints.com/Gallery](https://influentialpoints.com/Gallery/Eriosoma_lanigerum_Woolly_apple_aphid.htm)); BL 1.2-2.6 mm.  On roots, trunk or branches, often causing deformation and cancer-like swellings of bark.  It is a severe pest of apple (eg. Weber & Brown 1988), and may also be found on Cotoneaster and Pyracantha, and more rarely on Cydonia, Crataegus, Pyrus and Sorbus, but is not so injurious to these plants. Anholocyclic populations, sometimes with an apparently abortive sexual phase, occur on apple throughout the world, overwintering on the roots (see Blackman & Eastop 2000, p. 271). Alate sexuparae producing oviparae and males on apple are reported from various parts of the world, and eggs may be laid on apple leaves (e.g. Fotedar & Kapur 1943, Asante 1994, Sandanayaka & Bus 2005), but there is no firm evidence that these are capable of hatching, and it unlikely that fundatrices would be able to develop on apple and complete the holocycle.

Siciunguis decima Zhang & Qiao, described from apterae and alatae (sexuparae?) and causing heavy damage to apple in China (G. Zhang et al. 1999b) seems likely to be a synonym.

 In North America, aphids of the E. lanigerum group induce leaf rosette galls on Ulmus americana, but there is still doubt about the relationship of these to apple-feeding populations.  Smith (1985) successfully transferred alatae from such galls to apple.  However, alatae indistinguishable from those of E. lanigerum were obtained from reddish pink leaf curls on U. alata, and these would not transfer to apple but successfully colonised Crataegus uniflora.  Similar aphids occur in leaf-cluster galls on sterile elms in Australia (Fisk et al. 1992).

The ecology and natural enemies of E, lanigerum on apple were studied by Bouchard et al. (1984; Quebec, Canada), Gontijo et al. (2012; Washington, USA), Thakur et al. (1988; India) and von Kogler (1989; Germany).  Aphelinus mali is a widespread specialised parasitoid (but Aphelinus gossypii, which parasitises a wide range of hosts including Aphis and Rhopalosiphum spp., have often been misidentified as A. mali).  Lavandero et al. (2011) studied genetic variability in the aphid and its parasitoid in Chile, Timm et al. (2005) studied its genetic diversity in South Africa, and Zhou et al. (2015) analysed the genetic diversity and structure of the populations introduced into China. Ruiz-Montoya et al. (2015) studied morphometric and allozyme variation in populations collected on Pyracantha koidzumii in Mexico. A study of predation by earwigs was made by Mueller et al. (1988). Costa et al. (2014) compared performance parameters of four clones of E. lanigerum in Australia. Davidson (1913) made a detailed study of morphology and anatomy. M.Su et al. (2016) studied the distribution and functioning of the wax gland pores. The complete mitochondrial genome has been published (Y. Wang et al. 2016a). See Molinari (1986) for a general review. 2n=12.

Eriosoma mimicum Hottes & Frison   

On Ulmus spp. (americana, rubra) in eastern North America, probably forming leaf-curl galls.  Alatae were collected in June, migrating to an unknown host (Hottes & Frison 1931, Smith 1985).  Georgiaphis maxsoni is probably a synonym.

Eriosoma (Mimaphidus) pyricola Baker & Davidson   

Galls on Ulmus spp. (americana, procera) are clusters of bloated leaf tissue like those of E. lanuginosum (see Alfieri 1920; as inopinatum). The fundatrix and apterous fundatrigeniae are grey, emigrant alatae produced in second and third generations are brown with pale yellow abdomen (cf. lanuginosum); BL 1.3-2.4 mm.  Migration occurs in June-July to fibrous rootlets of Pyrus communis or Cydonia.  Apterous exules are yellowish pink when immature, pink to red when adult, rather sparsely clothed with filamentous wax (Baker & Davidson 1916); BL 1.3-2.0 mm.  Sexuparae are shiny dark green to brown, and return to elm bark in September-October.  In southern Europe (Italy, Yugoslavia), Turkey, and introduced into south-east Australia, Tasmania, New Zealand, USA (western and some north-eastern states), Canada (British Columbia), South America (Argentina, Chile) and (probably) South Africa.  Swenson (1971) studied the influence of the secondary host on sexupara production. This aphid is often confused with E. lanuginosum in the literature.  E. alabastrum Pashchenko (1988), described from U. japonica in Siberia, is very similar and possibly a synonym. It also seems likely that E. dilanuginosum Zhang (1980b), described from U. pumila in China, and with all morphs including the apterous exules on Pyrus now described (Qiao et al. 1999a; and again by Qiao et al. 2001b under the name Siciunguis novena), is this species. If this is so, then a record of E. dilanuginosum from Kazakhstan (Kadyrbekov 2018a) may also be ascribable to E. pyricola.

Tetraneura nigriabdominalis (Sasaki)  (= T. akinire)    

Galls are stalked, hairy, elongate, spindle- or pouch-shaped, 15-40 mm high, usually with a pointed apex (fig. 134E), usually bicoloured green and rose-red when mature (see influentialpoints.com). They occur on various Ulmus spp. (canescens, japonica, parvifolia, procera, pumila) in southern and south-east Europe (including Malta – Mifsud et al. 2009), south-west Asia (Iran, Georgia), Kazakhstan (Kadyrbekov 2014e), China, Korea and Japan. It is also in eastern USA on U. minor (Stoetzel 1987, as akinire), and in western USA (California) on U. pumila and hybrid elms (S. Dreistadt, pers.comm.). Galls on Ulmus sp. on high ground in Pakistan (Naumann-Etienne & Remaudière 1995, as akinire) are probably also this species. Alatae (BL 1.4-2.3 mm) (fig. 117E) leave the gall through lateral slits in May-July to found ant-attended colonies on the roots of Poaceae (including Cynodon, Digitaria, Echinochloa, Oryza, Saccharum, Setaria). Apterae on grass roots are greenish‑ or brownish‑white; BL 1.5-2.5 mm. Their presence on the roots of some hosts is indicated by a reddish-purple discoloration of the leaves.

This species is known particularly as a pest of rice (Blackman & Eastop 2000), but many of the references to nigriabdominalis, e.g. in Africa, the Middle East, India and south-east Asia, are referable to T. fusiformis. W. Lee et al. (2012b) distinguished Japanese populations of T. nigriabdominalis (referred to as “Type A” in their paper) from those of T. fusiformis (“Type B”) by their differing mitochondrial COI sequences. Tanaka (1961) studied its host preferences, although he may have had a mixture of T. nigriabdominalis and T. fusiformis. Galli & Bonvicini-Pagliai (1998) studied its relations with ants. Enoki (1986) studied resistance to this aphid in U. japonica. The male genitalia were described and illustrated by Wieczorek (2012). Hille Ris Lambers' (1970b) descriptions of gall generations under this name (his 'Group I material') should be referred to T. fusiformis (Eastop & Blackman 2005). Populations in China were described as a subspecies, T. nigriabdominalis ssp. shanxiensis Zhang & Zhang (as T. akinire ssp.). 2n = 18 (in gall generations); however Galli & Manicardi (1998) reported karyotype variation from 2n =13 to 19.

Kaltenbachiella ulmifusa (Walsh & Riley)  

Galls on Ulmus rubra are large, spindle-shaped, bag-like, about 2.5 cm long, green when young and becoming straw-coloured when mature, projecting upward from mid-rib of leaf (fig. 134I and Patch 1910b).  Emigrant alatae, BL 1.4-1.5 mm, with media either unbranched or once-branched, leave galls in June-July to found colonies on roots of Lamiaceae; successful transfers were made to Lycopus virginicus (Smith 1985). Apterous exules are yellowish orange with wax-wool (C.F. Smith, pers. comm.); BL unrecorded. Distributed throughout the range of U. rubra in North America, and recently reported (on Ulmus) in China (Jiang et al. 2004).

Colopha graminis (Monell)  

Forming cockscomb-like galls on upper surfaces of leaves of Ulmus spp. (americana, rubra) on the leaf lamina between the veins (Hottes & Frison 1931 and see influential points/gallery).  Alatae (BL 1.0-1.6 mm) emerge in June-July, migrating to found colonies on roots, stems and leaves of Poaceae, e.g. Aira caespitosa and Agrostis plumosa, from which it was originally described (Monell 1882), and  Leersia virginica (Patch, 1910b).  An attempted transfer to Eragrostis was unsuccessful (Patch 1910b, cf. ulmicola).  Apterae on secondary hosts live in grey woolly wax (see influential points/gallery), and have BL 1.2-1.8 mm. Sexuparae develop to adult on the leaves of the secondary host, returning to elm in October (Patch 1910b).  Widely distributed in North America.  Some authors (e.g. Palmer 1952) have synonymised graminis with ulmicola, and apterae on secondary hosts cannot be separated, but Smith (1985) considered that there was sufficient evidence to regard the two species as distinct. 

Colopha ulmicola (Fitch)   

Forming elongate cockscomb-like galls, pale green tinged with brown, apparently indistinguishable from those of C. graminis, on leaves of Ulmus spp. (americana, rubra, thomasii; fig. 134C).  Alatae (BL 1.0-1.6 mm) emerge in June-July and fly to Eragrostis spp., giving rise to colonies with flocculent wax on the upper leaves and stems. Possibly other Poaceae are also colonised, including Panicum and Zea (but not Leersia? - see Patch 1910b).  Apterae on secondary hosts are reddish brown, BL 1.2-1.8 mm. Sexuparae return to elm in September-November (Patch 1910b).  It is apparently widely distributed in North America, but records may be confused with those of C. graminis.

Prociphilus caryae caryae (Fitch) (=alnifoliae Williams) 

Spring populations (fundatrices + immature alatae) cup or curl the leaves of Amelanchier spp. and turn them yellow or whitish.  (Records from Crataegus are probably due to misidentification, particularly confusion with P. corrugatans.)  Emigrant alatae (BL 2.7-3.3 mm) fly in June to colonise roots of Pinus sp(p), sexuparae returning to Amelanchier in September-October.  In western USA and Canada (British Columbia).  (No field observations have been made of these western populations on pine roots, but Smith (1969) obtained colonies readily on Pinus strobus in the laboratory, and sexuparae collected on P. monticola in British Columbia (BMNH collection, leg  G. Shrimpton) appear to be this species.)  Similar aphids in eastern USA are regarded as a subspecies:-

Prociphilus caryae ssp. fitchii Baker & Davidson   

Spring populations (fundatrix + immature alatae) cause cupping and curling of leaves of Malus spp. (domestica, angustifolia) and Amelanchier spp. (see [influentialpoints.com/Gallery](https://influentialpoints.com/Gallery/Prociphilus_caryae_apple-pine_root_aphid.htm)). Emigrant alatae (BL 1.8-3.3 mm) migrate in June to found ant-attended colonies on roots of Pinus strobus.  Sexuparae return to the primary hosts in October-November where they deposit sexuales in bark crevices near base of tree or in nearby leaf litter (Smith 1969).  Widely distributed in eastern North America. Parthenogenetic populations also persist throughout the year on white pine roots.  A closely-related form, P. caryae ssp. arbutifoliae, forms spring populations on Photinia (= Heteromeles) arbutifolia in California, from which alatae (BL 2.9-4.1 mm) migrate to an unknown secondary host, probably pine roots.  (Records of P. caryae fitchii on Lonicera in India (A.K. Ghosh et al. 1981, A.K. Ghosh 1984b) apply to P. himalayensis.)

Aphids on the world's plants