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Aphids on birch

Blackman & Eastop list about 72 species of aphids  as feeding on birches worldwide, and provides formal identification keys for aphids on Betula. Of those, only 18 species occur on silver birch (Betula pendula) and/or downy birch (Betula pubescens) in Europe.

The species below are those we have found most frequently, listed in rough order of abundance. Assistance on identifying the two species of birch is given below.   

Betulaphis quadrituberculata (Small downy birch aphid)

Betulaphis quadrituberculata apterae are pale yellowish green, to pale yellow, to almost white. In autumn they may have patches of darker pigment. The antennae are shorter than the body (cf. Calaphis flava  which is often found on the same leaves, and has antennae longer than the body). All dorsal body hairs of the apterae are usually long and capitate, although there are forms with hairs on abdominal tergites 1-4 much shorter (cf. Calaphis flava which has short, and inconspicuous, spinal and pleural hairs). The siphunculi are smooth truncate conical with a strongly flared apical rim. The cauda is broadly rounded and subtriangular, projecting slightly beyond the deeply cleft subanal plate. The body length of Betulaphis quadrituberculata apterae is 1.5-2.0 mm.

 

Alate Betulaphis quadrituberculata are broadly similar to the apterae, but the dorsal hairs are nearly all fine and acute, not capitate unless on abdominal tergite 8. Antennal segment III has a single row of 8-21 transverse, oval, distinctly fringed secondary rhinaria. Males are dark and apterous with rather long antennae. Oviparae have a pigmented dorsal sclerotic pattern, and have the posterior abdominal segments produced into an elongate ovipositor-like structure.

They are mainly found on the undersides of leaves of downy birch (Betula pubescens), but they also occur on silver birch (Betula pendula) and occasionally on grey alder (Alnus incana). Betulaphis quadrituberculata is widely distributed across Europe through Asia to China, and has been introduced to North America.

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Euceraphis betulae (Silver birch aphid)

Immatures are green with conspicuous short black-tipped siphunculi. Adult winged viviparae have a pale green to pale yellow abdomen and are covered with bluish-white wax. The head and thorax of winged viviparae are black above and below and the legs and antennae are usually quite dark. Note that recently moulted specimens may be pale and lack wax. The dorsal abdomen may be unmarked, or have transverse black bands (common in spring and autumn) or black patches on abdominal tergites 4 and 5. The presence of dark cross bands in spring distinguishes specimens from Euceraphis punctipennis. The body length of winged viviparae is 3.0-4.2 mm.

 

The silver birch aphid lives on the undersides of leaves of silver birch (Betula pendula). Sexual forms occur from September to November. It occurs throughout Europe and has been introduced to North America and Australia.

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Euceraphis punctipennis (Downy birch aphid)

Adult winged forms have a pale green abdomen and are covered with bluish-white wax. The head and thorax are dark brown. Dorsal black patches when present are usually confined to abdominal tergites 4 and 5. Dark cross bands are never present in spring (distinguishes specimens from Euceraphis betulae, at least in spring!). The body length of winged viviparae is 3.0-4.8 mm.

The downy birch aphid lives on the undersides of leaves of downy birch (Betula pubescens). Sexual forms occur in October and November. It occurs throughout Europe.

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Symydobius oblongus (Shiny birch aphid)

The wingless vivipara (shown in the picture) is shiny dark brown with no wax covering. The antennae are brown apart from the basal parts of segments 4-6 which are conspicuously pale. They are slightly shorter than the length of the body with a terminal process that is shorter than the base of the last antennal segment. The siphunculi are pale, short and truncate. The body length of wingless viviparae is 2.0-3.5 mm. The winged vivipara has the wing veins brownish bordered and a dorsal pattern of broad dark transverse bands on each tergite.

 

The shiny birch aphid is found on twigs, young stems and branches of both the silver birch (Betula pendula) and the downy birch (Betula pubescens). Sexual forms occur in October-November. The species is found throughout Europe and across Asia.

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Calaphis flava (Yellow dark-veined birch aphid)

The apterae of Calaphis flava are pale green or yellowish with dark tips to the antennal segments, femoral-tibial joints, tibial apices and tarsi. The alate has the wing veins dark, but less dark than in Calaphis betulicola. The siphunculi are entirely pale (rarely with slightly dusky tips), in contrast to Calaphis betulicola which has dark tips to the siphunculi.

 

Calaphis flava favours small bushes of downy birch (Betula pubescens), but also found on young growth of larger trees and of other birch species. It is widespread in Europe eastward in Asia to Siberia and has been introduced to South Africa, Australia and North America.

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Calaphis betulicola (Black-tipped dark-veined birch aphid)

The apterae in life are pale green or yellowish, with dark apices to antennal segments, femoro-tibial joints, tibial apices and tarsi. The head and thorax are pale. The siphunculi are pale but with dark brown tips (usually distinguishes from Calaphis flava, see below, which has the siphunculi pale or a little dusky at the flange). The antennae are longer than the body and the terminal process is clearly longer than the base of the last antennal segment. Most secondary rhinaria on antennal segment III are placed towards the middle of the segment. They are not near the base, which gives a more reliable means to distinguish betulicola from flava. Their body length is 2.0 to 2.3 mm. Winged individuals have characteristically darkened wing veins, and their siphunculi have the apical halves dark brown to black.

 

Calaphis betulicola is found on the undersides of leaves of Betula spp., especially on Betula pubescens, usually on seedlings and small trees less than 1 meter high. It has been recorded as living on Betula nana in Scotland and Sweden. It is distributed from northern Europe across Russia to China and Japan, as well as in the USA and Canada.

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Callipterinella calliptera (Black banded birch aphid)

Callipterinella calliptera apterae (see first picture below) are yellowish green to bluish-green, usually with dark transverse bands on all tergites. The antennal terminal process is about 1.75 times the length of the base of the last antennal segment. The body length of Callipterinella calliptera apterae is 1.5-2.5 mm.

 

Alates (see second picture above) have dorsal markings less well developed. Immature Callipterinella calliptera are yellowish-green with rows of dark tubercles on the abdominal dorsum.

Black banded birch aphids are found in ant-attended groups on the young shoots and under leaves of birch (Betula spp.), sometimes inside leaves sewn up by lepidopterous larvae. Callipterinella calliptera is found on both silver birch (Betula pendula) and downy birch (Betula pubescens) in Europe, and on other birch species in east Asia. Oviparae and alate males occur in September-October. It occurs throughout Europe and across Asia, and has been introduced to North America.

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Callipterinella tuberculata (Red banded birch aphid)

Callipterinella tuberculata apterae are usually yellowish with a brown head, a reddish-brown dorsal band over the front of the abdomen and a dark quadratic patch on abdominal tergites 4-6. However, the dark markings are very variable. The dorsum has dark, strong hairs and spinules on each segment. The antennae may have five or six segments. The antennal terminal process is 1.7-2.8 times longer than the base of the last antennal segment. The siphunculi are dusky with rows of small spinules. The cauda is very short with only a slight constriction. The body length of Callipterinella tuberculata apterae is 2.3-2.5 mm.

 

Winged forms of Callipterinella tuberculata have reddish brown patches on the dorsum of the first abdominal segment and irregular small brown sclerites on posterior abdominal tergites, but no transverse bands.

Red banded birch aphids are found in colonies on young growth and scattered on older leaves of silver birch (Betula pendula). In Europe they are restricted to this one species of birch, but in Siberia apterous Callipterinella with a dorsal quadrate patch similar to Callipterinella tuberculata have been found on several different Betula species. Apterous males and oviparae are found in September. This species is found across Europe and (probably) in East Siberia and China.

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Glyphina betulae (Green birch thelaxid)

Wingless viviparae are dark green to almost black with a pale spinal stripe and four pale spots. The dorsum has wart-like cuticular ornamentation. The immature stages are green. The body length of wingless viviparae is 1.2-2.0 mm.

 

The green birch thelaxid does not host alternate but lives in colonies on young shoots of birch (Betula spp., especially silver birch (Betula pendula). It may occasionally also be found on alder ( Alnus spp.). They are usually ant-attended. The life cycle is shortened with oviparae appearing in July, and apterous males in August. The species is found throughout Europe, and across Asia to Japan. It has been introduced to North America where it is now widespread.

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Glyphina pseudoschrankiana (Brown birch thelaxid)

Wingless viviparae are black with variable white markings, usually two spots on each side and traces of a spinal stripe. The dorsum has short wrinkles sometimes appearing reticulated. The body length of wingless viviparae is 1.5-1.8 mm. Immature stages are brown.

 

The brown birch thelaxid does not host alternate, but lives in colonies on the young shoots, of downy birch (Betula pubescens). It tends to prefer young trees and is usually attended by ants. The life cycle is shortened with sexual forms occurring in July, and eggs laid in August.

The species occurs in north-west Europe and Japan.

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Clethrobius comes (Brown hairy birch aphid)

Clethrobius comes are large hairy elongate brown aphids. All adult viviparae and males are winged; the ovipara is wingless. The antennae are shorter than the body. The abdominal dorsum has pigmentation confined to marginal sclerites plus a few bands. There are also bands of light wax pulverulence on the abdomen. The siphunculi are short and truncate, and the cauda is knobbed. The mature winged viviparae are large, the body length being 4.1-4.4 mm.

In the literature the hairy birch aphid is recorded as being rare in the UK forming clusters on branches and twigs of Birch (Betula spp.), often where the new growth is dying back, or on twigs of Alder (Alnus spp.) overhanging streams. We have found it not uncommonly on birch in locations in Surrey, Hampshire, and East Sussex in the UK.

Sexual forms develop in October-November. The populations on alder are regarded by some as a separate species, Clethrobius giganteus, and attempts to transfer aphids from birch to alder have not succeeded. However, no consistent morphological differences have been found. The species occurs throughout Europe and across Asia to China, Korea and Japan.

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Monaphis antennata (Solitary birch aphid)

Adult winged forms are green, with very long thick antennae that are black except at the base. The terminal process of the antennae is nine times as long as the base of the last antennal segment. The siphunculi are very short with a flange. The cauda is tongue shaped and not constricted. The forewing has an elongate dark pterostigma . The body length of winged viviparae is 3.3-4.3 mm. Immatures are cryptic, and usually lie along the mid-ribs on the upper sides of leaves.

 

Monaphis antennata live solitarily on birch (Betula spp.). They migrate to the undersides of the leaves for the final moult. Sexual forms occur in September-October. They are found in Europe, eastward across Asia to Siberia, China and Japan.

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Hamamelistes betulinus (Birch blister aphid)

Wingless females are greenish or dark brown to black and are normally covered in white wax as shown in the first picture below. The second picture shows specimens in alcohol without the wax. They have short, 3- or 4-segmented antennae. In European populations, they lack siphuncular pores, although siphunculi are present in some generations in Japan. The body length of wingless viviparae is about 1.5 mm. Winged females have 5-segmented antennae and pigmented siphuncular pores. The body length of alates is 1.3-2.0 mm.

 

In Europe and northern Asia, the birch blister aphid does not produce sexual forms and does not host alternate. It feeds on the undersides of birch leaves, mainly silver birch (Betula pendula), causing pale yellowish blisters to develop on the upper surfaces. It overwinters as first instar larvae on the twigs. In Japan, there is host alternation between the primary host forms develop on the leaves of Hamamelis and eggs are laid on twigs and trunks. These hatch the following year and the developing fundatrices induce coral-like galls to develop from flower buds. Winged forms migrate to birch.

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Species of birch

We cover two species of birch, silver birch (Betula pendula) and downy birch (Betula pubescens). Silver birch is more common on dry sandy soils, its shoots are hairless and warty and the leaf margins are coarsely double toothed (see below).

Downy birch is more common on wet poorly drained soils, the shoots are downy or hairy (see below) and the leaf margins are finely serrated.

Acknowledgements

We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994)  and Blackman & Eastop (2006)  supplemented with Blackman (1974) , Stroyan (1977) , Stroyan (1984) , Blackman & Eastop (1984) , Heie (1980-1995) , Dixon & Thieme (2007)  and Blackman (2010) . We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure  provided by Blackman & Eastop (2006).

Useful weblinks 

References

  •  Blackman, R.L. & Eastop, V.F. Aphids on the world's plants An online identification and information guide. Full text