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American hophornbeam aphidOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution
Adult apterae of Macrosiphum pseudocoryli are green with mostly black siphunculi. Their antennae are markedly longer than the body (1.29-1.73 times). Antennal segment III has 2-7 secondary rhinaria in a row, and the longest hairs on antennal segment III are 0.5-0.7 times the basal diameter of the segment. The apical rostral segment (RIV+V) is 1.4-1.8 times as long as the second hind tarsal segment (HTII) and bears 14-18 accessory hairs. There are no dark markings on the dorsum (cf. Macrosiphum coryli, which has the abdomen green, but suffused with dark reddish-brown pigment laterally and posteriorly). Spinal and marginal tubercles are present on some segments. The bases of the femora are pale, the distal part of the femora and central parts of the tibiae are brown, and the apices of tibiae & tarsi are dark brown to black. The tarsal segments have 3 hairs. The siphunculi are black except for the base which is pale (cf. Macrosiphum coryli, which has the siphunculi wholly black), and they are not swollen (cf. Illinoia corylina & Illinoia macgillivrae, which both have slightly but distinctly swollen siphunculi). The siphunculi have a subapical zone of polygonal reticulation, and are usually more than twice the length of the cauda. The body length of adult Macrosiphum pseudocoryli apterae is 2.4-3.6 mm.
Images above by permission, copyright Claude Pilon, all rights reserved.
The alate Macrosiphum pseudocoryli (not pictured) has a brown head and thorax, but is otherwise similarly-colored to the aptera. Antennal segment III bears 12-19 secondary rhinaria in a row along one side on the basal 0.8-0.9 of the segment. Immatures (see picture below) are similarly colored to adults, but are usually somewhat paler and have dusky siphunculi (note young immatures of Macrosiphum coryli are also green, but without the dark reddish brown pigment of the adults, and so may be confused with immature Macrosiphum pseudocoryli).
Image above by permission, copyright Claude Pilon, all rights reserved.
Macrosiphum pseudocoryli is found on young growth and undersides of leaves of American hophornbeam (Ostrya virginiana) and hazel (Corylus species). Oviparae have been collected in Virginia in late September, so the population is assumed to overwinter in the egg stage. The species is found in north-eastern USA and across southern Canada.
Other aphids on the same host
Macrosiphum pseudocoryli has been recorded on 1 species of Ostrya (Ostrya virginiana).
Macrosiphum pseudocoryli has been recorded on 2 species of Corylus (Corylus americana, Corylus cornuta).