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Hawkweed aphidOn this page: Identification & Distribution Biology & Ecology Colour Other aphids on the same host
Identification & Distribution
Adult apterae of Nasonovia pilosellae (see first picture below) are medium-sized yellowish-green or pinkish to blackish, rather shiny aphids. There are dark intersegmental sclerites between each abdominal segment, as well as either an ill-defined patch, or broad transverse bands of dark dorsal pigmentation on the abdomen. The ratio of the length of the terminal process of the last antennal segment to its base ranges from 5.7-8.0 (cf. Nasonovia ribisnigri, in which the ratio of the length of the terminal process of the last antennal segment to its base ranges from 7.0-11.4). The secondary rhinaria on the third antennal segment spread out along one side of the segment (see micrograph below) (cf.Nasonovia ribisnigri, where the secondary rhinaria on the third antennal segment tend to be concentrated on the basal part of the segment). The first segment of their hind tarsus has two hairs. Their siphunculi are cylindrical and rather long, with little or no apical reticulation The cauda of Nasonovia pilosellae is elongate and rather blunt finger-shaped. The body length of the Nasonovia pilosellae adult aptera is 1.2-2.5 mm.
The images below show an aptera in alcohol, and the secondary rhinaria spread out along antennal segment III.
The hawkweed aphid is monoecious holocyclic on a few related species of hawkweed, namely the orange hawkweed (Pilosella aurantiaca), common hawkweed (Hieracium lachenalii) and the mouse-ear hawkweed (Hieracium pilosella). We have found them especially frequent on mouse-ear hawkweed. In spring they live inside upwardly rolled leaves, moving later in the year to the stems and flowers. Oviparae and apterous males are produced in October. They are distributed throughout Europe and over to central Asia.
Biology & Ecology
Most authorities describe Nasonovia pilosellae as being 'shining green to black', but we have also found a pink form occurring along with the greenish forms. The picture below shows an alate of the pink form.
The immatures of the pink forms are similarly coloured (see below).
Other aphids on same host:
Nasonovia pilosellae has been recorded from 7 Hieracium species, and 2 Pilosella species (Pilosella caespitosa, Pilosella officinarum).