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Bicolored frostweed aphidOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution
Adult apterae of Uroleucon verbesinae are either shiny black or bright shiny red (cf. Uroleucon rurale, which is greenish-brown - see note below). Their antennae are slightly longer than the body and are uniformly black. The apical rostral segment (RIV+V) is very long and thin, 1.6-1.9 times as long as the second hind tarsal segment, and more than 4 times longer than its basal width (cf. Uroleucon rurale, which has RIV+V 1.2-1.56 times the length of the second hind tarsal segment, and less than 4 times its basal width). The bases of the femora are pale yellow; the rest of the femora and all the tibiae & tarsi are black. The dorsal hairs are without dark basal scleroites. Dusky antesiphuncular sclerites are present, which on the live insect only show up on the red apterae. The siphunculi are long and black, more than 1.5 times the length of the cauda which is also black (cf. Uroleucon ambrosiae, which has siphunculi less than 1.5 times as long as the cauda, which is pale). The siphunculi have reticulation on the distal 0.23-0.35 of length, comprising numerous small polygonal cells.
Note: Hottes & Frison (1931) describe Uroleucon rurale as having the head and mesothorax often brownish green and the abdomen very dark green, whereas Olive (1963) describes it as being grass-green. Suspected Uroleucon rurale on Verbesina in Virginia, USA pictured in Bugguide are predominantly brown-green.
First image copyright C.A. Ivy, second image copyright Miriam Vaughn, both under a CC BY-NC 3.0 license.
Immatures of the red form (see second picture above) are a slightly paler red than the adults, whilst immatures of the black form (see first picture below) are dark reddish brown. Like the adult apterae, alatae of Uroleucon verbesinae (see second picture below) are either shining black or bright red. Alatae have 25-36 secondary rhinaria scattered along all of antennal segment III (cf. Uroleucon rurale alatae, which have 13-27 secondary rhinaria, mostly on the basal two thirds of segment III).
First image copyright Chuck Sexton, second image copyright C.A. Ivy, both under a CC BY-NC 3.0 license.
Uroleucon verbesinae appears to be restricted to feeding on frostweed (Verbesina virginica) in the USA, but in Honduras it has been found on Verbesina myriocephala. Boudreaux (1948) notes that it usually feeds under the leaves, moving to the stems when crowded on the leaves (cf. Uroleucon rurale, which feeds preferably on the stem). As far as is known, Uroleucon verbesinae is monoecious holocyclic. Uroleucon rurale, the only other Uroleucon so far known to feed on Verbesina virginica, has a more northerly distribution being found in the eastern USA from South Carolina northwards.
Other aphids on the same host
Blackman & Eastop list 2 species of aphid as feeding on frostweed (Verbesina virginica) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) does not list either of these as occurring in Britain (Show British list).