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Genus ChaitophorusPoplar & willow aphidsOn this page: Chaitophorus capreae crucis horii beuthani leucomelas macrostachys neglectus nigrae nigricentrus nudus pallipes populeti populialbae populicola ramicola salicti salijaponicus niger saliniger stevensis tremulae truncatus viminalis viminicola vitellinaeChaitophorus [Chaitophorini]Chaitophorus aphids are very hairy, small to medium-sized aphids with short, stump-shaped siphunculi. The dorsal cuticle of the apterae is often largely sclerotized. Alates often have dark segmental cross-bands and marginal sclerites. The cauda is usually knobbed. There are about 90 species of Chaitophorus aphids worldwide with individual species feeding on either Populus (poplar) or Salix (willow) spp. in the Salicaceae. Chaitophorus capreae (Pale sallow leaf aphid) Europe, East & Central AsiaChaitophorus capreae apterae are white to yellowish-white to bluish-green (see pictures below) with no distinct dark dorsal abdominal markings (cf. Chaitophorus salicti, which has more-or-less extensive dark markings on the dorsum). Antennal segment III has only 0-4 hairs, the longest of which are 5-20 µm long. The body is not markedly narrow: the body length 1.8-2.1 times the maximum body width (cf. Chaitophorus horii beuthani, which is more elongate with a body length 2.1-2.5 times the maximum body width, and occurs on narrow-leaved Salix species). The dorsum and appendages bear numerous furcate (=forked) hairs (see second picture below). The cauda has a distinctly knobbed apex. The body length of Chaitophorus capreae is 0.8-1.9 mm.
Chaitophorus capreae alatae (not pictured) are yellowish white with no solid dark segmental bands on the abdominal tergites. Instead there is a much broken pattern on the middle tergites not forming anything like a mid-dorsal rectangular patch. The pale sallow leaf aphid lives mostly on sallows (broad-leaved Salix spp.) especially great sallow (Salix caprea) and grey sallow (Salix cinerea). Aphids are usually scattered on the undersides of leaves although dense colonies can occasionally develop. They are not attended by ants (cf. Chaitophorus salicti and Chaitophorus ramicola, which are usually attended by ants). Brown oviparae and deep yellow apterous males (see pictures below) occur in October-November. Chaitophorus capreae is widespread in Europe, and eastward to Central Asia. Chaitophorus crucis (Sandbar willow aphid) Western North AmericaAdult apterae of Chaitophorus crucis (see yellowish green aphids below) are pale green, with darker green areas marking out a large broad light yellow-green cross, comprised of a pale spinal stripe from the base of the head to the cauda, and a pale transverse band across tergite II. Eyes are dark red, and siphunculi and cauda are pale. Appendages including femora are pale, except for brown pigment on antennal segments V & VI, and the tarsi (cf. Chaitophorus utahensis, which has the hind femora much darker than the tergum). Antennal tubercles are undeveloped. The antennae are slightly longer than 0.5 times body length, with the terminal process nearly twice the base of antennal segment VI; the longest hair on segment III is up to 1.5 times the basal diameter of that segment. The base of antennal segment VI has 2-5 hairs (cf. Chaitophorus macrostachyae, which has 7-14 hairs on the base of VI). The rostrum extends to the hind coxae, with the apical rostral segment about the same length as the second hind tarsus. First tarsal segments usually have 5(-7) hairs. Abdominal hairs are arranged in two irregular transverse rows on tergites I-V (VI), and one row on tergites (VI) VII-VIII. Siphunculi are reticulate, and are slightly longer than antennal segment I. The cauda is rounded, almost semicircular and the anal plate is entire. Body length of adult Chaitophorus crucis apterae is about 1.3 mm. Note: dark reddish brown aphids are another species
Images above copyright Jesse Rorabaugh, no rights reserved. The alate Chaitophorus crucis (not pictured) has a dark thorax, and a green abdomen with dark markings. Antennal segments I-III are pale to dusky, and segments IV-VI are dark; secondary rhinaria are distributed 4-9 on segment III, 1-3 on segment IV, & 1-2 on segment V. The eyes are red. The species was first found and described early in the 20th century; They were in dense colonies feeding on the undersides of leaves of northwest sandbar willow (Salix sassilifolia) along the banks of the Santa Clara River, Santa Paula, California. It has not yet been recorded on other species of willow, but may be so in future. The aphids shown above were found in San Bernadino County, California, and would appear to be the first records of this species since it was originally described. Chaitophorus horii beuthani (Pale willow leaf aphid) Europe, AsiaAdult apterae of Chaitophorus horii ssp. beuthani are whitish to pale yellow. The body is rather long and narrow, with the body length 2.1-2.5 times the maximum width. Antennal segment III has only 0-4 hairs, the longest of which are only 5-20 μm long. Abdominal tergites 1-5 each have 12-30 smaller accessory hairs between the long spinal, pleural and marginal pairs. The cauda has a distinctly knobbed apex.
Alatae (not shown here) have black dorsal abdominal cross-bands. Chaitophorus horii ssp. beuthani lives on the underside of the leaves of narrow-leaved willow such as Salix viminalis and Salix fragilis. It usually feeds from the leaf midrib. Chaitophorus leucomelas (Black poplar leaf aphid) CosmopolitanAdult apterae of Chaitophorus leucomelas are elongate oval in shape and the background colour varies from green to yellow. They usually have two dark stripes along the sides which tend to merge on abdominal tergite V (see first picture below), but sometimes the stripes may be divided segmentally (see second picture below), or may be missing altogether. Whatever the pattern, there are (nearly) always broad pale spinal and marginal areas. The antennae are half as long as the body of the aphid, with the terminal process of antennal segment VI 2.7-3.3 times the base of that segment. The fused apical rostral segment (RIV+V) is 0.8-1.2 times the length of the second hind tarsal segment (HTII). Abdominal tergite I is usually free from tergites II-VI (cf. Chaitophorus tremulae, which has abdominal tergite I fused with tergites II-VI). The hind tibiae are without any pseudosensoria (cf. Chaitophorus populeti, which has a small number of pseudosensoria on the hind tibiae even on the adult vivipara). The short truncate siphunculi are dark at least apically (cf. Chaitophorus populialbae, which has entirely pale siphunculi). The cauda is rounded and very pale. The body length of adult Chaitophorus leucomelas apterae ranges from 1.2 to 2.4 mm.
Chaitophorus leucomelas alatae have dark brown dorsal abdominal cross-bands of varying width (see two pictures below) and separate marginal sclerites visible in the images. The host plant of Chaitophorus leucomelas in Europe is mainly black poplar (Populus nigra) and related species and hybrids, but in North America a wider range of species is colonised. They feed on young shoots of Populus spp. in spring, and later under leaves, in leaves stuck together by moth larvae, or in leaf galls vacated by other insects. The black poplar leaf aphid is commonly ant-attended. Chaitophorus leucomelas is widely distributed in Europe, North Africa and Asia, and has been introduced to South Africa and North and South America. Chaitophorus macrostachyae (Pale-centred willow aphid.htm) Western North AmericaAdult apterae of Chaitophorus macrostachyae (see first picture below) are broadly oval, greyish to brownish or black, often with a pale central dorsal area (cf. Chaitophorus nigricentrus in eastern USA, which is darker centrally). Siphunculi are pale to dusky. Antennal segments are brown, apart from segment III which is pale yellow; legs are brown with the anterior pair paler. Antennal tubercles are undeveloped. The base of antennal segment VI has 7-14 hairs (cf. Chaitophorus crucis, which has only 2-5 hairs on the base of VI). Antennal segment III is without secondary rhinaria, and its longest hair is nearly twice the basal diameter of that segment. The rostrum extends beyond the third pair of coxae. Each first tarsal segment has 7, sometimes 6, hairs (cf. Chaitophorus nigrae, which normally has 5 hairs on that segment). Abdominal hairs are blunt, toothed or pointed, arranged in 2 or 3 irregular rows on tergites I-VI, and in single rows on VII and VIII. Tergites I-VI also have a spinal and pleural spine, noticeably thicker than other hairs. Siphunculi are reticulate, and about as long as antennal segment I. The cauda is rounded or arc-shaped, and the anal plate is entire. Body length of adult apterae is 2.0-2.8 mm. Immature Chaitophorus macrostachyae (see second picture above) are yellowish or reddish with brown markings.
Images above, copyright Jesse Rorabaugh no rights reserved. Chaitophorus macrostachyae is mostly associated with northwest sandbar willow (Salix sessilifolia = Salix macrostachya). It has also been found on some other willow species in western North America, such as sandbar willow (Salix exigua), and red willow (Salix laevigata). Chaitophorus macrostachyae was first described by Essig (1912) who found it feeding on the young stems of Salix sessilifolia, often on the same stems as Chaitophorus crucis (which feed on the leaves). It is assumed to be monoecious holocyclic. Chaitophorus macrostachyae has since frequently been found on the trunk and roots of Salix at or below ground level. This species is restricted to western North America. Chaitophorus neglectus (Dark-striped aspen aphid.htm) North AmericaAdult apterae of Chaitophorus neglectus (see two pictures below) are usually yellowish-green to green, with a somewhat brownish head, prothorax and posterior abdomen, and typically with a pair of dark pleural stripes of varying width running from the thorax to abdominal tergite VI. Occasionally the body may be completely green without darker dorsal markings, other than dark green flecks. Antennal segments I, II and (usually) IV-VI are dark or dusky, with the others pale (cf. Chaitophorus populifolii, which usually has all antennal segments pale). The antennae bear long hairs, about 3 times the basal diameter of antennal segment III. Abdominal tergites I-VI are always fused, whilst tergite VII is free or fused to segment VI (cf. Chaitophorus leucomelas, which has abdominal tergite I almost always free from tergites II-VI.) Chaitophorus neglectus has the hairs on each tergite arranged in two irregular rows (cf. Chaitophorus stevensis, which has the hairs arranged on each tergite more-or-less in a single row). Most of the long spinal and pleural hairs on tergites I-VII have pointed or blunt apices (cf. Chaitophorus populifolii, which has most of such hairs with expanded or bifurcate apices) The siphunculi are pale and reticulate, about as long as antennal segment I. The cauda is tongue shaped or distinctly knobbed (cf. Chaitophorus populicola, which has the cauda rounded with no trace of constriction). The anal plate is entire. The body length of adult Chaitophorus neglectus apterae is 1.7-2.5 mm.
Images above copyright (2011), Her Majesty the Queen in Right of Canada, Agriculture & Agri-Food Canada. Chaitophorus neglectus alatae have dark dorsal abdominal cross-bands and dark siphunculi (cf. Chaitophorus populifolii, which have fewer bars and pale siphunculi). The bars on Chaitophorus neglectus may be fused on tergites III-VI to give a black quadrate patch. The tarsi and last two pairs of femora are brown, but otherwise their legs are pale. Chaitophorus neglectus feed on aspens (Populus tremuloides, Populus grandidentata) and on eastern cottonwood (Populus deltoides) (cf. Chaitophorus populifolii, which occurs mainly on Populus balsamifera, and only rarely on Populus tremuloides). Feeding sites include the upper and undersides of leaves, or in leaves folded and stuck together by other insects. Colonies are often quite large, and are not attended by ants, although they are sometimes mixed with Chaitophorus stevensis, which is ant-attended. Chaitophorus neglectus is holocyclic, with oviparae and both apterous and alate males occurring in September-November. It is widely distributed in North America. Chaitophorus nigrae (Pale-streaked willow aphid.htm) North AmericaAdult apterae of Chaitophorus nigrae are variably pigmented. At maximum pigmentation they are entirely shiny black (see first picture below). More often they are dark with a more or less marked pale median stripe from head to tergite VI (see second picture below). At a minimum they are pale with brownish pleural intersegmental sclerites, but abdominal tergites VII & VIII are always evenly dark-pigmented across the tergite (cf.
First and third images above by permission, copyright Claude Pilon, all rights reserved. Chaitophorus nigrae alatae (see third picture above) have dark dorsal abdominal cross-bands, which often coalesce between abdominal tergites II-VI. They have 9-17 secondary rhinaria irregularly placed on antennal segment III, with some also on segments IV and V. The terminal process is 2-3 times as long as base of the last antennal segment. Chaitophorus nigrae lives in sometimes large colonies on leaves and petioles of new growth of various willow (Salix) species, especially black willow (Salix nigra). They are usually attended by ants. Large, pale oviparae and alate males occur in September-November, and the species overwinters as eggs on willow. Chaitophorus nigrae is widely distributed in North America, extending from Alaska eastwards to New Brunswick and southwards to California and North Carolina. Chaitophorus nigricentrus (Dark-centred willow aphid.htm) North AmericaAdult apterae of Chaitophorus nigricentrus are broadly oval, dark yellow-brown to pinkish-brown to blackish-brown, with the central part of their dorsum darker than its margins (see first picture below). The base of antennal segment VI has 2-5 hairs, and the hairs on antennal segment III are mostly long and fine-pointed. The fused apical rostral segment (RIV+V) is 0.125 mm long and has 2-4 accessory hairs. The dorsal cuticle is wholly or partly reticulated (see first picture below) (cf. Chaitophorus stevensis, which has no reticulate ornamentation, but has irregularly placed blunt nodules). The last two pairs of legs tend to be darker than the front legs. The hind femora are paler than the tergites, and the first tarsal segment (HTI) has 7 (rarely 6) hairs. The short, stump-shaped siphunculi are pale brown and reticulated. The cauda is broadly rounded with no trace of any constriction. The body length of adult Chaitophorus nigricentrus apterae is 1.5-1.8 mm.
Both images above by permission, copyright Claude Pilon, all rights reserved. Chaitophorus nigricentrus lives in large colonies on the second-year growth of Salix species. The photos on this page show them feeding on the stems of dewy-stem willow (Salix irrorata). Judging from Claude Pilon's photographs (e.g. see second picture above) Chaitophorus nigricentrus is, at least sometimes, ant-attended. Little seems to be known about this species, but it probably produces sexuales in autumn. Chaitophorus nigricentrus has so far been recorded from Ontario & Montreal (these observations) in Canada, and from Pennsylvania in USA - but not from outside North America. Chaitophorus nudus (Poplar stem aphid.htm) North AmericaAdult apterae of Chaitophorus nudus are broadly oval in shape, and are coloured dark brown to shiny black (see first picture below). Their antennae and legs are wholly dark. The longest hairs on antennal segment III are 1.5 times as long as the basal diameter of segment III. Abdominal tergites II-VII are wholly sclerotized and fused into a solid tergum (=dorsal part of the segment). The fused apical rostral segment (RIV+V) is 0.2 mm long, and has 2-4 accessory hairs. Tergites II-VII each have 3-5 spinal hairs and some marginal hairs, but they have no pleural hairs (cf. both Chaitophorus populicola and Chaitophorus nodulosus, where tergites II-VII have spinal, marginal and pleural hairs). The short, somewhat truncate siphunculi are pale or a little dusky. The cauda is rounded without any trace of constriction. The body length of adult apterae is 2.0-2.6 mm. Immature Chaitophorus nudus are greyish-brown.
All three images above by permission, copyright Claude Pilon, all rights reserved. Chaitophorus nudus alatae have the dorsal abdomen blackish or dark green with black bars or cross-bands (see second picture above). The dark forewing veins are broadly grey bordered, with a more-or-less conspicuous black pterostigmal spot (see third picture above). There are 11-27 secondary rhinaria on antennal segment III, 2-8 on segment IV, 0-2 on segment V, and none on antennal segment VI. Chaitophorus nudus is found usually in rather small colonies on the trunk of saplings (and possibly branches of more mature trees) of quaking aspen (Populus tremuloides) (cf. Chaitophorus populicola, which is only found on the young shoots, developing leaves and leaf petioles of poplars, Populus spp.). Sexuales (large pale oviparae and alate males) develop in autumn. Poplar stem aphids are often attended by ants (see picture above). Chaitophorus nudus is a North American species, being found in southern Canada (Manitoba, Ontario, Quebec) and western and northern USA (Colorado, Pennsylvania). Chaitophorus pallipes (Black and yellow willow aphid.htm) North AmericaAdult apterae of Chaitophorus pallipes are yellow with slight green mottling and broad black pleural stripes (see first picture below). The base of antennal segment VI has 2, or rarely 3, hairs, and the longest hair on antennal segment III is about 3 times as long as the basal diameter of that segment. The fused apical rostral segment (RIV+V) is 0.125 mm long, with 1-3 hairs. Abdominal tergites I-VIII all have pale spinal areas (cf. Chaitophorus nigrae, where abdominal tergites VII & VIII are always evenly dark-pigmented across each tergite). Abdominal segments I-VI are all fused. The femora are usually pale, at least on the fore and middle legs. The siphunculi of Chaitophorus pallipes are unpigmented, with a clear surrounding area (cf. Chaitophorus nigrae, which has dusky siphunculi, without any clear surrounding area on the dorsum). The cauda is not knobbed, but is tongue-shaped with margins slighly diverging towards the base (cf. Chaitophorus viminalis, where the cauda is markedly knobbed). The body length of adult Chaitophorus pallipes apterae is 1.8-2.4 mm. First instar immatures are yellow or yellowish green (cf. Chaitophorus nigrae, whose first instars are usually black or sometimes brown or very dark green). Later instars often have green pleural markings (see second picture below of Chaitophorus pallipes colony with immatures).
Both images above by permission, copyright Claude Pilon, all rights reserved. Alatae of Chaitophorus pallipes are greenish-yellow with black dorsal abdominal cross-bands (see two pictures below). There are 9-16 secondary rhinaria on antennal segment III, 0-6 on segment IV, and 0-2 on segment antennal V. Chaitophorus pallipes is found on the young growth of American pussy willow (Salix discolor), and other Salix species. Their colonies are usually ant-attended. Chaitophorus pallipes is a North American species, occuring in Canada, and recorded from several, mainly western, states in the USA (Idaho, Montana, California, Oregon and North Carolina). Chaitophorus populeti (Poplar shoot aphid) Europe, AsiaAdult Chaitophorus populeti apterae are oval, shiny dark green to black. There is sometimes a paler stripe along the midline of the thorax and the front of the abdomen. There are separate bands on the pre- and meso-notum and abdominal tergites 7-8. The antennae are more than half the length of the body. The terminal process is about twice the length of the base of the last antennal segment. The siphunculi are dark. The body length of Chaitophorus populeti is 1.5-2.9 mm.
Chaitophorus populeti alates (see second picture above) are dark green to black with broad brown dorsal abdominal cross-bands and marginal plates. The wing veins are brown-shadowed. The poplar shoot aphid lives on the young shoots and terminal leaf petioles of various poplar (Populus) species, especially of the aspen (Populus tremula) and white poplar (Populus alba). It is usually attended by ants. Oviparae and males occur in October-November. Chaitophorus populeti is found throughout the Palaearctic region, but has not been found in the USA or Canada. Chaitophorus populialbae (Poplar leaf aphid) Europe, Asia, Africa, North AmericaAdult Chaitophorus populialbae apterae are small, short-bodied, oval, greenish to yellowish white, often with small green spots (see first picture below). The head and tips of antennal segments and tarsi are light brown. The antennae are 0.6-0.9 times the length of the body, and the terminal process is 1.7-3.3 times as long as the base of the last antennal segment. The siphunculi are pale. The body length of Chaitophorus populialbae is 1.0-2.3 mm.
The alate (see second picture above) has the head, thorax and antennae black, and the abdomen green with dark brown cross-bands, often with bands coalescing on abdominal tergites 2-6. Poplar leaf aphids live in (usually) small colonies on undersides of leaves of various Poplars (Populus spp.) and are sometimes ant-attended. Oviparae and males occur in September-November. Chaitophorus populialbae occur throughout the Palaearctic region, parts of Africa, and are introduced and widespread in North America. Chaitophorus populicola (American poplar leaf aphid) North AmericaAdult apterae of Chaitophorus populicola are yellow brown (see first picture below) to shiny black (see second picture below). Their antennal terminal process is normally longer than the base of antennal segment VI. The longest hair on antennal segment III is about twice as long as the basal diameter of that segment. The fused apical rostral segment (RIV+V) is 0.15 mm long with 2-6 accessory hairs. Abdominal tergites II-VII are wholly sclerotised and fused into a dorsal plate. There is no pale median line on the sclerotic pronotum nor on the abdominal segments, but the metanotum and abdominal tergite I-III may be partly or wholly pale. Abdominal tergites II-VII each have pleural as well as spinal and marginal hairs (cf. Chaitophorus nudus which has no pleural hairs on these tergites). There are no evident spinules or nodules on the dorsum (cf. Chaitophorus nodulosus, which has the abdominal tergum evenly spinulose or nodulose). Part or most of the dorsal hairs on the abdomen are tapered to points, blunt, or with chisel-shaped, often forked apices (cf. Chaitophorus populicola ssp. patchae which has all hairs fine and pointed). Their legs are dark brown to black. The siphunculi are small pale truncate cylinders. The cauda is rounded without any trace of a constriction. The body length of adult apterae is 2.0-2.5 mm. Immature Chaitophorus populicola are reddish brown or dark brown, with a distinctive pattern of dark and pale areas (see pictures of immatures with adults below).
First image above copyright Kenneth Frank under a Creative Commons License Chaitophorus populicola alatae (see pictures below) have dorsal abdominal cross bars or bands. Their forewings have dark veins with conspicuous brown-borders. Chaitophorus populicola has been recorded from many different poplar (Populus) species. It feeds and forms colonies only in association with the apical meristem. Dense colonies may develop on young shoots, developing leaves, and leaf petioles (cf. Chaitophorus nudus, which is only found around the trunks of poplar saplings, and probably on the branches of more mature trees). Feeding by Chaitophorus populicola on young leaves induces part of the leaf to fold over, thus partially enclosing the colony. This species is nearly always attended by ants (see third picture above), which remove their honeydew and protect the aphids from predators. Chaitophorus populicola is distributed throughout most of North America, but has not so far been invasive outside America, neither in Europe nor Asia. This may be because, in the Palearctic zone, its niche (ant-attended feeding on the apical meristem of Populus) is taken by the poplar shoot aphid, Chaitophorus populeti, which is widely distributed and simarly common. Chaitophorus ramicola (Sallow stem aphid) Europe, AsiaAdult apterae of Chaitophorus ramicola (see first picture below) are broadly oval, mainly very dull greyish olive to black with a more-or-less distinct broad pale spinal stripe (cf. the dark form of Chaitophorus salicti, which has only a faint very narrow spinal stripe). The partially darkened cross bands on abdominal tergites I and II are separate from III, and tergites III-VI may also have separate or only partially fused bands (cf. Chaitophorus capreae, which does not have any darkened cross bands). The apical rostral segment (RIV+V) is 1.0-1.3 times as long as the second hind tarsal segment. The siphunculi are pale with darker rims, and the cauda is bluntly conical with only a slight constriction delimiting the apical part (cf. Chaitophorus salicti, which has a cauda with a distinct constriction dividing it into a triangular basal part and a globular apical knob). The body length of adult Chaitophorus ramicola apterae is 1.4-2.6 mm.
Third image above copyright Marco de Haas, all rights reserved. Chaitophorus ramicola alates (see second picture above) are brownish olive with narrow dark dorsal abdominal cross-bands. Immature sallow stem aphids (see third picture above) are variable in colour from straw yellow to greyish olive to wine red. Chaitophorus ramicola feeds on the thin stems of willows (Salix species), mainly the broad-leaved species such as great sallow (Salix caprea) and grey sallow (Salix cinerea) (cf. Chaitophorus salicti, which feeds on the leaves of sallow). Chaitophorus ramicola is usually attended by ants. Sexual forms (apterous males and oviparae) develop in October. The sallow stem aphid is found in north, central and eastern Europe, Iran and Kazakhstan, and has now been found in Britain. Chaitophorus salicti (Sallow leaf-vein aphid) Europe, Asia, Africa, North AmericaIn spring adult Chaitophorus salicti apterae are black with a faint narrow spinal stripe (see first picture below). In summer adult apterae are light yellowish-green with reddish-brown or greenish-black dorsal markings (see second picture below). The last two fused rostral segments (RIV+V) are 1.1 to 1.6 times as long as the second hind tarsal segment (HTII) (cf. Chaitophorus salijaponicus niger, which has RIV+V 0.8-1.07 times the length of HTII). Abdominal tergite I is separate from tergites II-VI, which are fused together (see micrographs of apterae in alcohol, below) (cf. Chaitophorus ramicola, which has abdominal tergite II separate from III, and tergites III-VI often have separate or partially-fused bands). The first tarsal segment normally has 5, or occasionally 6, hairs. The siphunculi are dusky or dark, and are sometimes surrounded by a membranous ring, at other times fused solidly into the dorsal carapace. The pale cauda has a distinct constriction dividing it into a triangular basal part and a globular apical knob. Chaitophorus salicti is a small species. The body length of adult apterae is only 1.3-1.8 mm.
Alatae (not pictured) are dark, with broad dorsal abdominal cross-bands. Immature Chaitophorus salicti are brownish-grey (spring form) or pale yellowish-green (summer form). Sallow leaf-vein aphids live along the veins on the underside of leaves of various sallows (including Salix caprea, Salix cinerea, Salix aurita) (cf. Chaitophorus ramicola which lives on the thinner stems of sallows. They are usually ant-attended (see third picture top) (cf. Chaitophorus capreae, which is not attended by ants). Oviparae and apterous males occur in September-October. Chaitophorus salicti occur throughout the Palaearctic region, parts of Africa, and are introduced and widespread in North America. Chaitophorus salijaponicus niger (Dark willow leaf aphid) Europe, AsiaAdult apterae of Chaitophorus salijaponicus niger are usually blackish-brown with a pale ring around the bases of the siphunculi (see first picture below). Abdominal tergites 1-6 or 2-6 are fused into a solid carapace. The dorsal cuticle is sculptured with wavy lines of small bead-like or denticular spinules that tend to form reticulations in the mid-thoracic and anterior abdominal region. The antennae, legs and cauda are mainly pale.
Alates (see second picture above) are dark, with broad dorsal abdominal cross-bands. Nymphs are wine red with a yellowish suffusion around the siphunculi. The second picture above shows a Chaitophorus salijaponicus niger alate - the body is fairly uniformly dark, but the pale legs and antennae are useful distinguishing features. Dark willow leaf aphids live separately or in small colonies on leaves of willow (narrow-leaved Salix spp.), only rarely visited by ants. Oviparae and males occur in September-November. Whether males are apterous or alate seems to depend on geographical location. Chaitophorus salijaponicus niger are found in Europe and across Asia to Siberia, but are replaced by a different subspecies in China and Japan. Chaitophorus saliniger (Oriental dark willow aphid) East AsiaAdult apterae of Chaitophorus saliniger (see first picture below) are shining blackish-brown to black, with blackish siphunculi and a rather pale cauda; the femora and distal parts of antennae are dark. Antennae are short, 0.43 times body length, with the terminal process l.0-2.5 (usually l.6) times as long as base of the segment. Longest hairs on antennal segment III are 2.7-3.7 times the mid-diameter of that segment. The rostrum does not reach the middle coxae, and the apical rostral segment is 0.9-1.1 times as long as the second hind tarsal segment. The hind tibiae have a swollen base, with 2-17 small pseudosensoria on the swollen part - see note below (cf. Chaitophorus salijaponicus & Chaitophorus matsumurai, which do not have a basal swollen part on the hind tibiae). The first tarsal segment has 5 hairs ventrally. The abdominal tergum is sclerotic with microstructure consisting of blunt, marginally more acute, nodules. Abdominal tergites II-VI are fused together, segment VII is not well defined from VI, but VIII is clearly separate. Marginal sclerites are distinct. Siphunculi are reticulated, 0.14-0.25 as long as the second hind tarsal segment. The cauda is faintly constricted, with 7 hairs. Body length of adult Chaitophorus saliniger apterae is 1.0-1.8 mm. Immatures (see smaller aphids in first picture below) have a characteristic yellowish suffusion around the siphunculi.
First and third images copyright Seo, H. et al., NIBR, The Aphids of Korea I, The alate vivipara of Chaitophorus saliniger (see second picture above) has the head and thorax black sclerotic, and large, black bands on all abdominal segments. Antennae are about 0.59 times body length. Secondary rhinaria are distributed 6-10 on antennal segment III, 2-4 on segment IV, and 0-1 on segment V. Siphunculi are 0.29-0.77 times the second hind tarsal segment. Body is about 1.51 mm. in length. Chaitophorus saliniger is monoecious on narrow-leafed Salix spp., such as weeping willow (Salix babylonica). It feeds on the young leaves, petioles or shoot tips. It is usually a very common species, and is often ant-attended. The species is holocyclic, and apterous males and oviparae occur in November-December. Chaitophorus saliniger is found in Japan, China and Korea. Chaitophorus stevensis (Speckled poplar aphid) North AmericaAdult apterae of Chaitophorus stevensis are pale green with dark green (see first picture below) or dark reddish-brown (see second picture below) markings on the abdomen (note that these darker markings are unsclerotized, and are not visible in clarified slide mounts). Their antennae are mainly pale, although sometimes the apex of the base of segment IV and the apex of the terminal process are darkened. The longest hairs on antennal segment III are mostly less than twice as long as basal diameter of that segment. The fused apical rostral segment is 0.075-0.100 mm long, with 1-3 secondary hairs. Abdominal tergite I is frequently fused with abdominal tergites II-VI. Dorsal ornamentation consists of rather evenly-distributed separate roundish nodules. The hairs of abdominal tergites I-VIII are very variable in size and form; they are arranged on each tergite more-or-less in a single row (cf. Chaitophorus neglectus and Chaitophorus populifolii, in which hairs on each tergite are arranged in two irregular rows). Abdominal tergite VIII has 7-12 hairs (cf. Chaitophorus neglectus and Chaitophorus populifolii, in which tergite VIII usually has more than 12 hairs). The siphunculi are pale, short, and truncate . The cauda is knobbed, and is clearly visible in the adult apterae in the first two pictures below (the aphid with the purplish-red markings in the second picture is quite large, but is still a fourth instar nymph so the cauda is not yet fully developed). The body length of adult apterae is 1.6-2.0 mm. Immature Chaitophorus stevensis are pale green or reddish-brown, with or without darker markings. Note: Richards (1972) covers this species under the synonym Chaitophorus delicatus.
Both images above by permission, copyright Claude Pilon, all rights reserved. Chaitophorus stevensis alatae have 8-15 secondary rhinaria on antennal segment III (which are scattered, not in a row), there are 0-5 on antennal segment IV, and 0-1 on segment V. The sclerotized bars on abdominal tergites III-VI are much wider than those on tergites I and II (see second picture below). Thes bars are often more-or-less fused to form a central dorsal patch. The siphunculi of alatae are dark. Chaitophorus stevensis feeds on cottonwoods (mainly Populus deltoides and Populus angustifolia) and aspens (Populus grandidentata and Populus tremuloides). It is usually attended by ants (cf. Chaitophorus neglectus, which is not ant attended). Blackman indicates it is frequently associated with leaf-fold galls of another aphid, Thecabius populiconduplifolius. Chaitophorus stevensis is found throughout North America, but not elsewhere. Chaitophorus tremulae (Aspen leaf aphid) EuropeChaitophorus tremulae apterae are elongate oval with the dorsum solidly blackish sclerotic, rather densely sculptured with denticular spinules, and very often with a paler line along the mid-dorsum (see first picture below). Except in the fundatrix, abdominal tergite 1 is more or less completely fused with the carapace on tergites 2-6. The antennae are usually dark and half the length of the body, and the terminal process is 2.1-2.8 times as long as the base of the last antennal segment. The siphunculi are dark and the legs are brown with the hind pair darker. The body length of Chaitophorus tremulae is 1.2-2.5 mm.
Alates have very broad black dorsal abdominal cross-bands which tend to coalesce. Immature Chaitophorus tremulae are bright green. Aspen leaf aphids live in small colonies on undersides of leaves of Aspen (Populus tremula) and a few related species of Populus. They have also been found in leaves spun together by other insects, or in leaf-nest galls made by another group of aphids (Pemphiginae). Oviparae and alate males occur in October. Chaitophorus tremulae occurs throughout Europe and as subspecies in the Far East. Chaitophorus truncatus (Green willow leaf aphid) Europe, Middle EastChaitophorus truncatus apterae are elongate oval in shape. In spring they are pale green with three darker green interrupted longitudinal stripes. In early summer and autumn some are solidly blackish on the dorsum. Their antennae are half the length of the body, and the terminal process is 2.2-3.2 times as long as the base of the last antennal segment. The siphunculi are pale, as are the legs and antennae. The body length of Chaitophorus truncatus is 1.2-2.4 mm.
Images copyright www.aphotofauna.com all rights reserved. Chaitophorus truncatus alates have separate, narrow, often broken bars across abdominal segments 3-8. The green willow leaf aphid lives in small colonies on leavers of various narrow leaved willows including Salix purpurea, Salix amygdalina, Salix alba and Salix triandra. Apterous males and oviparae can be found in autumn. Chaitophorus truncatus does not host alternate, and is not ant attended. It is distributed throughout Europe and east to Iran and Kazakhstan. Chaitophorus viminalis (Small black and green willow aphid) North AmericaThe adult apterae of Chaitophorus viminalis are of variable colour in life, usually pale green to yellow in spring with darker green pleural stripes (see two pictures below). In summer they are often dark brown to black. (cf. Chaitophorus nigrae where the apterae are usually black, often with a paler spinal area; and cf. Chaitophorus pusillus where the apterae are whitish). The hairs on antennal segment III are very much longer on the inner side than on the outer side. The apical rostral segment (R IV+V) is short, less than 1.5 times its basal width and 0.6-0.8 times the length of the second hind tarsal segment (HTII). The first tarsal segments usually have 6-7 hairs (cf. Chaitophorus pusillus where the first tarsal segments mostly have 5 hairs). The siphunculi are pale, short and stump-shaped. The cauda is markedly knobbed with an almost globular or faintly elongated, small knob (cf. Chaitophorus nigrae where the cauda is very little knobbed, although sometimes there is a slight neck). The body length of adult apterae is 1.3-1.9 mm. Immatures are greenish-yellow, with the older nymphs having more prominent pleural stripes. Hille Ris Lambers (1960) has noted that the species has often been misidentified in the literature, with some of those identified as Chaitophorus viminalis in fact being Chaitophorus stevensis, Chaitophorus populifolii or Chaitophorus nigrae.
First and third images above by permission, copyright Claude Pilon, all rights reserved. Alatae (not pictured) have dark dorsal abdominal cross-bands which often coalesce into a central patch. Chaitophorus viminalis is found on leaves and young growth of various narrow-leafed willow species (e.g. Salix lucida & Salix nigra). Oviparae and alate males occur in October-November. They are frequently attended by ants (see pictures above & below). Chaitophorus viminalis is found throughout North America. Chaitophorus viminicola (Dusky long-haired willow aphid) Eastern North AmericaAdult apterae of Chaitophorus viminicola are elongate oval in shape (see first picture below). They are more or less blackish, with a vague paler median stripe which from the pronotum, usually down to abdominal tergite III, (it runs to tergite VI in our pictures below). Their antennae are dark brown, apart from most of segment III which is pale yellow. The length of antennal segment III is 3.0-4.2 times that of the base of antennal segment VI. The antennal hairs are rather numerous, fine, and long: the hairs on the inner side of segment III are up to 3 times the basal diameter of that segment, and the few hairs on its outer side are up to twice that diameter. The apical rostral segment (RIV+V) is rather slender, 1.0-1.2 times the length of the second hind tarsal segment (HTII), and has 10 or more hairs. Tergites I-VI are fused. The tergum has no reticulate ornamentation, but has irregularly placed blunt nodules (cf. Chaitophorus nigrae, which has a reticulate pattern on the pleural areas of abdominal tergites I-VI). The dorsal hairs are extremely long with fine, acute, apices (these long dorsal hairs can be readily seen in the first two pictures below). The femora of their fore-legs are yellowish brown, but the middle and hind hind legs have very dark femora - darker than the dorsal shield (cf. Chaitophorus longipes, which has all femora dark). All the tibiae have dark bases: they are brownish-yellow with slightly darkened apices. The first tarsal segment has 5 hairs (rarely 6) (cf. Chaitophorus viminalis, whose first tarsal segment has 6-7 hairs). The siphunculi are rather thin, pale brown, and placed on a small colourless membranous area. The cauda is slightly dark and very distinctly knobbed. The body length of adult Chaitophorus viminicola apterae is 1.9-2.5 mm.
Images above by permission, copyright Claude Pilon, all rights reserved. Alate viviparous females (not pictured) of Chaitophorus viminicola have a black sclerotic head and thorax. The abdomen has equally-wide, separate, black bands on all tergites, with rather small black marginal sclerites, and intersegmental dots. Antennal segment III is nearly smooth, and has 10-14 secondary rhinaria irregularly placed along one side; the other antennal segments have no secondary rhinaria. The terminal process of the alate is about 4 times the length of the base of antennal segment VI. Chaitophorus viminicola feed on willow (Salix) species. It has so far only been recorded on white willow (Salix alba) and black willow (Salix nigra), but is probably also found on several other native American species. They most likely overwinter as eggs, but sexual forms have not yet been found. Chaitophorus viminicola is found in eastern states of the USA and in Canada. Chaitophorus vitellinae (Willow stem aphid) Europe, AsiaAdult apterae of Chaitophorus vitellinae are rather broad yellow-green aphids with (in life) two darker pleural longitudinal lines, but rarely with any melanic dorsal suffusion. The antennal terminal process is less than twice as long as the base of antennal segment VI. Longer antennal hairs are rather evenly distributed round the circumference of segments III-V inclusive (cf. Chaitophorus salijaponicus niger and Chaitophorus truncatus, which have them primarily on the inner side of those segments). The dorsum is normally pale sclerotic, with abdominal tergites I-VI wholly or partly fused into a rather solid carapace with dense, coarse, irregular nodular sculpturing. The apical rostral segment (RIV+V) is about 1.1-1.2 times as long as the second hind tarsal segment (HTII) and bears 4-9 subsidiary hairs. The first tarsal joints have 6-7 hairs of which one is a medioapical sense-peg. The siphunculi are pale and short. The cauda has an indentation partially delimiting the rounded apical part. The body length of adult Chaitophorus vitellinae apterae is up to 2.1 mm. Note: one subspecies has been described, Chaitophorus vitellinae danubicus, which has a distinctly knobbed cauda and thickened dorsal hairs. It is found on white willow (Salix alba) in Romania, Czechoslovakia and Turkey.
Shown above are Chaitophorus vitellinae adult apterae, dark and pale form. Alatae of Chaitophorus vitellinae (not pictured) have rather narrow, evenly spaced transverse dark bands across the abdominal tergites. There are 3-10 secondary rhinaria on antennal segment III and, rarely, 1 or 2 on IV. Chaitophorus vitellinae is found on the young twigs and leaf petioles of narrow-leafed Salix spp., especially Salix alba. They are attended by ants. There is no host alternation and the species overwinters on willow in the egg stage. Apterous males and oviparae occur in September-October. Chaitophorus vitellinae is distributed throughout Europe, and east to west Siberia, Iran and Kazakhstan.
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