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Genus Symydobius

Shiny birch aphids

Species Overview: Genus Symydobius  Symydobius oblongus 

Genus Symydobius [Calaphidini]

Medium to large, rather shiny dark brown aphids. Both winged and wingless adult viviparous females occur and (unusually) they have a similar pattern of sclerotization. Siphunculi (when present) are small and truncate. Antennae are dark or with the basal half of the 4th and 5th segments conspicuously paler. Males are wingless, and oviparae have the posterior abdominal segments extended into an ovipositor-like structure.

Seven species forming colonies on the branches and twigs of birch and alder (Betulaceae). They have a sexual stage in their life cycle, but do not host alternate. They are always attended by ants.

 

Symydobius oblongus (Shiny birch aphid)

The aptera (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 apterae is 2.0-3.5 mm. The alate 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.

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

  •  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