Macrosiphum stanleyi

Identification & Distribution

Adult apterae of Macrosiphum stanleyi (see two pictures below; the first is a fundatrix) are spindle-shaped, light yellowish green, with pale dusky-tipped siphunculi and pale cauda. Appendages are pale except the tips of the tibiae, rostrum and antennae and the entire tarsi which are dark. The antennae are much longer than the body and bear relatively few (2-7) secondary rhinaria, located along the posterior margin. The rostrum reaches or surpasses the second pair of coxae, with the apical rostral segment (RIV+V) about the same length as the second hind tarsal segment (HTII). The siphunculi are long and pale with dusky tips, more than 3 times the caudal length, and slightly swollen just before the subapical zone of reticulation. The cauda is rather broad and short, tapering or nearly parallel-sided with a blunt tip, and bears 5 pairs of lateral and 2-3 pairs of dorsolateral hairs, and about 3 single dorsal ones. The body length of adult Macrosiphum stanleyi apterae is 3.0-4.4 mm. Immatures are lightly dusted with white wax.

Alatae of Macrosiphum stanleyi (not pictured) have a brown-black head and thorax, and a light green abdomen, with antennae reaching beyond the length of the cauda. Antennal segment III bears 12-18 secondary rhinaria, which vary greatly in size.

Macrosiphum stanleyi is a large, spindly, monoecious aphid found on the leaves and stems of elderberry (Sambucus spp.), including blue elder (Sambucus cerulea) and Pacific red elder (Sambucus pubens). All forms are quite active, and move about over the leaf surface when disturbed. The species is holocyclic. Palmer (1952) reports that oviparae and alate males occur in August in Colorado, but in British Columbia oviparae are present as early as June. Wilson (1915) found it common in the vicinity of Vancouver, British Columbia and Seattle, Washington, USA. Andrew Jensen has seen it in habitats from dry steep slopes of mountains in New Mexico to the deepest darkest understory of western Oregon rain forests. Macrosiphum stanleyi is found in western North America, from Colorado to Alaska.

Other aphids on the same host

Macrosiphum stanleyi has been recorded on 4 elderberry species (Sambucus callicarpa, Sambucus cerulea, Sambucus pubens, Sambucus racemosa).

• Blackman & Eastop list 2 species of aphid as feeding on blue elder (Sambucus caerulea worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 1 as occurring in Britain (Show British list).

• Blackman & Eastop only list 1 species of aphid (Macrosiphum stanleyi) as being recorded on pacific red elder (Sambucus callicarpa) and on scarlet elder (Sambucus pubens).

Acknowledgements We are grateful to Andrew Jensen for making his images of Macrosiphum stanleyi available for use under a creative commons licence. We have used the species accounts given by Wilson (1915) and Palmer (1952), together with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections as the source for the (summarized) taxonomic information we have presented. Any errors in information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks

References Palmer, M.A. (1952). Aphids of the Rocky Mountain Region: including primarily Colorado and Utah, but also bordering area composed of southern Wyoming, southeastern Idaho and northern New Mexico. Full text Wilson, H.F. (1915). Aphid notes from British Columbia Proceedings of the Entomological Society of British Columbia 5, 82-84 Full text