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Macgillivray's meadowsweet aphidOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution
Adult apterae of Illinoia macgillivrayae (not pictured) are pale yellowish-green slender spindle-shaped aphids. Their antennal tubercles are rather well developed, and diverging. The antennae are 1.10-1.25 times the body length; they get gradually darker from the pale base to the blackish apex, with the extreme apices of segments III and IV blackish. Antennal segment III has 1 or 2 rather flat secondary rhinaria. The rostrum reaches to halfway between the second and third pair of coxae, and the apical rostral segment (RIV+V) is 1.05-1.25 times the length of the second segment of the hind tarsi (HTII) (cf. Illinoia spiraeae, which has RIV+V 0.85-1.15 times HTII). The dorsal body hairs are very short and inconspicuous. The legs are long, yellowish, with dark apices to the tibiae. The first tarsal segments of all legs have 5 hairs. The siphunculi are pale, with tips somewhat dark. They have a slightly tapering base, and are then nearly cylindrical, before widening to a maximum in the distal quarter, where they are about 1.3 times as wide as the smallest diameter toward the base; they finally abruptly narrow to the reticulated area, which covers 0.08-0.11 of their length. The siphunculi are 2.35-2.60 times the caudal length (cf. Illinoia spiraeae, which has siphunculi 1.65-2.3 times as long as the cauda). The cauda is pale, with a bluntish apex and 7 hairs. The body length of adult Illinoia macgillivrayae apterae is 2.6-3.2 mm.
Note: Although in the text above we have given the means to differentiate Illinoia macgillivrayae from Illinoia spiraeae, Jensen suggests that specimens meeting these criteria may in fact represent just one variable polyphagous species that lives on woody and herbaceous plants in several families across western America.
Alatae of Illinoia macgillivrayae (see picture above) have a brown head and thorax and a green abdomen. They have 7-9 secondary rhinaria on antennal segment III.
Illinoia macgillivrayae was originally described by Hille Ris Lambers (1966) from specimens found in small colonies on the young leaves of (non-native) Indian hawthorn (Raphiolepis indica). As anticipated, the aphid was subsequently found on other Rosaceae such as the non-native Japanese quince (Chaenomeles japonica) and evergreen pear (Pyrus kawakamii); and the native ocean spray (Holodiscus discolor) and Spiraea sp. In addition it was found on beaked hazelnut (Corylus cornuta). Illinoia macgillivrayae is distributed through western USA and Canada.
Other aphids on the same host
Illinoia macgillivrayae has been recorded on 1 species of Corylus (Corylus cornuta).
Illinoia macgillivrayae has been recorded from 1 ocean spray species (Holodiscus discolor).
Illinoia macgillivrayae has been recorded on plants of the genus Spiraea, but not on any particular species.