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Uroleucon obscurum

Large hawkweed aphid

Identification & Distribution 

Identification & Distribution:

Adult apterae of Uroleucon obscurum are reddish brown to bronze with black antennae and siphunculi and a yellow cauda. The body hairs are rather long, and placed on distinct scleroites. The femora are yellow basally and black on the distal half. The tibiae have the basal half yellowish brown. The apical segment of the rostrum is 1.06-1.29 times the length of the second hind tarsal segment. The antennal terminal process is 3.8-6.2 times longer than the base of antennal segment 6. The siphunculi are 1.1-1.6 times the length of the cauda. The body length of an adult Uroleucon obscurum aptera is rather less than for most species at 1.8-3.7 mm.

The images below show clarified mounts of (first) an adult apterous Uroleucon obscurum and (second) an alate Uroleucon obscurum.

Clarified mount  by permission of Roger Blackman, copyright AWP  all rights reserved.

The large hawkweed aphid does not host alternate. It can be found on the upper parts of stems of hawkweed (Hieracium spp.). Sexual forms appear in September, and the species overwinters in the egg stage. Uroleucon obscurum is distributed throughout Europe and into 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).

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