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Pleotrichophorus pseudoglandulosusWestern bristly mugwort aphidOn this page: Identification & Distribution Other aphids on the same hostIdentification & DistributionAdult apterae of Pleotrichophorus pseudoglandulosus are pale bluish-green, with a frosted appearance. This is due the presence of numerous white funnel-shaped hairs on the dorsum, except along the median line. On the head, they have 16-29 such hairs with long distinct stems (cf. Pleotrichophorus decampus, mainly in southwest USA on Artemisia tridentata, which has 29-55 white funnel-shaped hairs on the head, many of them short or stemless). The head has moderately produced antennal tubercles, but the median frontal tubercle is rather small. The antennae are twice as long as the body. The hairs on antennal segment III are short, the longest being about 0.3 times the basal diameter of the segment. The rostrum reaches to between the second and third pairs of coxae. The apical rostral segment (RIV+V) is quite long and slender, about 1.25 times the second hind tarsal segment (HTII) and 0.13-0.16 mm in length (cf. Pleotrichophorus decampus, which has RIV+V 0.10-0.13 mm and Pleotrichophorus glandulosus which has RIV+V 0.11-0.12 mm.) The siphunculi are slightly bulbous just before the tip, and 2.61-3.44 times as long as the cauda (cf. Pleotrichophorus glandulosus, which has siphunculi 1.9-2.5 times the cauda). The cauda is slightly tapered, broadly rounded at the apex, and not constricted, bearing 2 pairs of lateral hairs and a single dorsal preapical one. The body length of Pleotrichophorus pseudoglandulosus adult apterae is 1.1-2.0 mm.
Images above by permission, copyright Claude Pilon, all rights reserved. The alate vivipara of Pleotrichophorus pseudoglandulosus (not pictured) has the head, pronotum and abdomen pale green and the thorax brown. The abdomen has brown, tranverse pleural intersegmental sclerites on tergites I-VII. The antennae are dusky from near the base of segment III, and dark from the apex of segment V. There are 10-19 secondary rhinaria on antennal segment III. The siphunculi are 2.3-2.8 times the cauda. The image below shows an adult aptera and a fourth-instar Pleotrichophorus pseudoglandulosus nymph, along with a unknown aphid species, possibly a dwarf Aphis gossypii.
Image above by permission, copyright Claude Pilon, all rights reserved. Pleotrichophorus pseudoglandulosus is monoecious holocyclic on the leaves and stems of several Artemisia species, especially fringed sagebrush (Artemisia frigida), white sage (Artemisia tridentata) and big sagebrush (Artemisia ludoviciana). Oviparae and apterous males have been found in the fall. Palmer (1952) reported it was common, but difficult to find on account of protective coloration, solitary habit and agility in escaping. Pleotrichophorus pseudoglandulosus has a wider distribution than the very similar Pleotrichophorus decampus (which is only in south-west USA), being found as far south west as California, USA and as far northeast as Manitoba in Canada. Other aphids on the same hostPleotrichophorus pseudoglandulosus has been recorded on 5 Artemisia species (Artemisia frigida, Artemisia ludoviciana, Artemisia mexicana, Artemisia tridentata, Artemisia vulgaris) and possibly Artemisia argyi.
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