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Genus Stomaphis

Giant stem aphids

Species Overview: Stomaphis   Stomaphis quercus 

Stomaphis [Lachnini]

Stomaphis are large or very large oval aphids which are characterized in the females by a very long rostrum. Their antennae are 6-segmented and densely hairy. Their siphunculi are pores on low, haired, cones. The second segment of the hind tarsus is rather long compared with other lachnids.  Males are small, apterous and have no mouthparts.

Stomaphis feed on the stems and roots of a variety of tree species, with most species on oak (Quercus), birch (Betula), maple (Acer), willow (Salix) and poplar (Populus).

 

Stomaphis quercus (Giant oak aphid)

Adult apterae of Stomaphis quercus are elongate oval shining dark brown. They have numerous densely placed, thin, erect hairs on the body, antennae and legs. The antennae are dark, about 0.4 times the length of the body, with segment 3 paler than the others. The rostrum is exceptionally long, in the adult nearly twice as long as the body. It is proportionally even longer in immatures. There are dark spinal spots on abdominal tergites I-VI and cross bars interrupted in the middle on tergites VII and VIII. The body length of apterae is 5.3-7.0 mm.

Image copyright Bernhard Seifert,  all rights reserved.

Given its size, the alate has rather small wings. Their wing veins have brown borders.

Stomaphis quercus is found on several species of oak (Quercus), and sometimes also on birch (Betula). It is always ant attended, normally by Lasius fuliginosus (see picture above), but sometimes by Lasius brunneus. Sexual forms occur in September-November. The species is rare in UK and may be locally extinct. Its stronghold was Breckland, East Anglia which is now largely under agriculture. It is found throughout Europe and in west Siberia.

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Acknowledgements

Our especial thanks to Bernhard Seifert (Senckenberg)  whose image we have reproduced above.

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 sp 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).

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