Uroleucon jaceicola

Identification & Distribution:

Apterae of Uroleucon jaceicola are dark bronze-brown. They have strong body hairs, pointed and placed on rather large scleroites. Their coxae are dark, but the legs are yellow apart from black knees and black apices to the tibiae (cf. Uroleucon jaceae which has wholly dark tibiae). The siphunculi of Uroleucon jaceicola are black, although they may be paler in summer than in spring. The siphunculi are 2.0-3.0 times the length of the cauda. The cauda is pale yellow with a dusky tip, and bears 9-18 hairs (cf. Uroleucon jaceae which has a black cauda). The body length of Uroleucon jaceicola apterae is 2.9-3.3 mm.

Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.

Uroleucon jaceicola lives on the stems of common knapweed (Centaurea nigra). In spring the yellow-legged knapweed aphid is found mainly low on stem, but moves to the upper parts later on. Oviparae and very dark apterous males of Uroleucon jaceicola have been found on the petioles of radical leaves in October. Uroleucon jaceicola is found in Europe, west Siberia and Central Asia.

Other aphids on same host:

Uroleucon jaceicola has been recorded from 10 Centaurea species.

• Blackman & Eastop list 7 or more aphid species as feeding on common knapweed (Centaurea nigra) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 7 as occurring in Britain (Show British list).

Acknowledgements Our particular thanks to Nigel Gilligan for past use of his image of this species and to Roger Blackman for images of his clarified slide mounts. Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made 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