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Uroleucon jaceicola

Yellow-legged knapweed aphid

On this page: Identification & Distribution  Other aphids on the same host 

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 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.

Image of aptera: guest image copyright Nigel Gilligan, all rights reserved.

The clarified slide mounts below are of adult viviparous female Uroleucon jaceicola : wingless, and winged.

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:

Blackman & Eastop list 7 or more aphid species  as feeding on common knapweed (Centaurea nigra) worldwide, and provide formal identification keys.

Of those aphid species, Baker (2015)  lists 7 as occurring in Britain: Acaudinum centaureae, Brachycaudus cardui,  Brachycaudus helichrysi,  Myzus cymbalariae, Trama troglodytes,  Uroleucon jaceae  and Uroleucon jaceicola.


Our particular thanks to Roger Blackman for images of his clarified slide mounts.

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).

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