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Genus Calaphis

Dark-veined birch aphids

Species Overview: Genus Calaphis  Calaphis flava  Calaphis betulicola 

Genus Calaphis [Calaphidini]

Delicate pale-coloured aphids with rather long thin legs. The antennal tubercles are well-developed and the antennae are longer than the body. They sometimes have distinctive markings and/or dark wing veins, and the radial sector in the forewing is absent or indistinct. In some Calaphis species all viviparae are alate but others have both apterous and alate viviparae. The genus is sometimes mis-spelt as Callaphis.

There are about 15 Calaphis species, 11 of which are in North America, two are European and one is east Asian. All except one live on birch (Betula spp.). They have a sexual stage in their life cycle, but do not host alternate and are usually not attended by ants.

 

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.

 

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.

 

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 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.

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

  •  Dixon, A.F.G. & Thieme, T. (2007). Aphids on deciduous trees. Naturalist's Handbooks 29. Richmond

  •  Stroyan, H.L.G. (1977). Homoptera: Aphidoidea (Part) - Chaitophoridae and Callaphidae. Handbooks for the identification of British insects. 2 (4a) Royal Entomological Society of London. Full text