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Genus Plocamaphis

Plocamaphis aphids

On this page: Genus Plocamaphis  Plocamaphis spx 

Plocamaphis [Macrosiphini]

Identification: Plocamaphis is a small genus comprising only five species. They are large rather sparsely hairy aphids, less hairy than Pterocomma  aphids to which they are related. Plocamaphis are brown or yellowish brown, but the colour is usually masked by dense floculent wax. They have flangeless siphunculi.

Plocamaphis feed low down on the stems or on the roots of willow (Salix). They are not ant attended, but sometimes occur in mixed colonies with ant-attended species such as Tuberolachnus salignus. 

 

Plocamaphis flocculosa (waxy willow aphid)

Identification & Distribution

Adult apterae of Plocamaphis flocculosa (see first picture below) are grey or yellowish grey and are more or less densely covered with white wax. The head, antennae, legs and part of the thorax are dark. The mesonotum and metanotum and abdominal tergites I-IV have rather large, dark, paired dorsal sclerites. There are well developed marginal tubercles present on the prothorax and abdominal tergites I-IV, and often also on V. The siphunculi are bright orange, and have a swollen distal part, with an extremely small aperture in the end of the rounded apex. They are quite long at 0.8-1.1 times the length of the second hind tarsal segment (cf. Plocamaphis amerinae in which the siphunculi are only 0.4-0.5 times the length of the second hind tarsal segment). The body length of the adult Plocamaphis flocculosa aptera is 3.1-5.0 mm.

Images copyright Andy Brown, all rights reserved.

The alate viviparous female lacks dark dorsal sclerites on the abdomen, the wing veins are bordered brownish and the siphunculi are more slender than in the apterae.

Four subspecies, distinguishable by the length of the siphunculi, have been recognised: the nearctic Plocamaphis flocculosa flocculosa and three palearctic subspecies Plocamaphis flocculosa brachysiphon, Plocamaphis flocculosa goernitzi and Plocamaphis flocculosa macrosiphon. These subspecies are of somewhat questionable validity given the wide range of variation within them. The pictures above show Plocamaphis flocculosa brachysiphon from Britain.

Plocamaphis flocculosa feeds on the trunk and branches of sallow (Salix caprea, Salix cinerea), black willow (Salix nigricans) and creeping willow (Salix repens) in Europe - and American pussy willow (Salix discolor) and arroyo willow (Salix lasiolepis) in North America. Oviparae and alate males of Plocamaphis flocculosa brachysiphon have been found in October. The large waxy willow aphid is found in Europe and North America, and has also been reported from China.

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Acknowledgements>

We especially thank Andy Brown for the photographs 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).

Useful weblinks 

References

  •  Blackman, R.L. & Eastop, V.F. (2006). Aphids on the world's herbaceous plants and shrubs. Vols 1 and 2. John Wiley & Sons.