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Pale pearly everlasting aphidOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution
Adult apterae of Illinoia richardsi are spindle-shaped, very pale green with a white wax dusting (cf. Uroleucon russellae, which is bronzy black with dark antennae). The apices of antennal segments, apices of tibiae and the tarsi are darker to blackish. The antennae are about 1.3-1.6 times as long as the body, and have 4-20 secondary rhinaria regularly placed in a row over basal 0.33-0.67 part of segment III. The rostrum reaches to just past the hind coxae. The apical rostral segment (RIV+V) is about 1.5-1.7 times as long as the second hind tarsal segment (HTII), and has 5-9 hairs besides the 3 apical pairs. There are rather large, flat spinal tubercles on the vertex and abdominal tergite VIII, and marginal tubercles on some or all of tergites II-V. The first tarsal joints all have 3 hairs. The siphunculi are about 2.25-2.50 times the caudal length, and have the apical 0.06 distinctly reticulated. They are swollen over the distal part up to 1.4 times the smallest diameter basal to it. The cauda is moderately blunt, not constricted, and with 7 long fine hairs. The body length of adult Illinoia richardsi apterae is 2.6-3.2 mm.
Note: A subspecies of Illinoia richardsi from California, namely Illinoia richardsi ssp. pacifica, has been described by Hille Ris Lambers (1966). It has thicker and less swollen siphunculi than the nominate species.
Alatae of Illinoia richardsi (not pictured) are also very pale, but have brownish head, thorax, and antennae; the legs are brownish but the femoral basal halves are pale. The secondary rhinaria on antennal segment III are in a row over nearly its whole length. The wings have rather dark brown wing veins. The siphunculi have a thinner stem than in the apterae, so that the swollen area is about 1.9 times as thick as the smallest diameter basal to it.
Illinoia richardsi has been found on the undersides of the leaves and in the inflorescences of pearly everlasting (Anaphalis margaritacea) and bicolored everlasting (Pseudognaphalium bioletti =Gnaphalium bicolor). It is often found on the flower stems with Uroleucon russellae The species is assumed to be monoecious holocyclic, but the sexual morphs have not been described. Illinoia richardsi is widely distributed in USA and Canada.
Other aphids on the same host
Illinoia richardsi has been recorded from 1 Anaphalis species (Anaphalis margaritacea).
Illinoia richardsi has been recorded from 1 Pseudognaphalium species (Pseudognaphalium bioletti).