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Aphidinae : Macrosiphini : Macrosiphum rudbeckiarum
 

 

Macrosiphum rudbeckiarum

Cockerell's green goldenglow aphid

On this page: Identification & Distribution Other aphids on the same host

Identification & Distribution

Adult apterae of Macrosiphum rudbeckiarum are light green with a darker median stripe. Their antennae have segments I & II pale, segments III-IV are light dusky with apices darker, and segment VI is dark. The femora are pale, the tibiae are pale, except near the apex where they are dusky, and the tarsi are dark. The siphunculi are pale with dusky tips, and the cauda is pale. The antennae, legs & siphunculi are darker in fall than in summer. Their antennal tubercles are very well developed, and a median frontal tubercle is also present. Antennal segment III bears 4-10 secondary rhinaria, and the hairs on segment III are about as long as that segment is wide. The antennal terminal process is about 6 times as long as that segment's base is wide. The rostrum extends just beyond the meso-coxae. The siphunculi are long and thin, pale, mainly cylindrical, but with a broader base, and with reticulation on the apical 0.11 (cf. Uroleucon rudbeckiae & Uroleucon nigrotuberculatum on Rudbeckia, which have rather thick, dark siphunculi, reticulated on the distal 0.25 or more). The siphunculi are about 2.3 times the caudal length, with an average length of 1.52 mm (1.14-1.64 mm) (cf. Macrosiphum euphorbiae on Rudbeckia, which has siphunculi less than 1.1 mm long). The cauda is elongate, tapering, with scarcely any tendency to constriction at its base, and bears three hairs on each side. The body length of adult Macrosiphum rudbeckiarum apterae is 2.9-3.9 (4.2) mm.

Images above copyright Andrew Jensen, under a creative common licence.

The alate Macrosiphum rudbeckiarum has a dusky green head and thorax, a darker brown meso- and metathorax and a pale green abdomen with a, usually faint, darker median stripe. There are 16-22 large oval or round secondary rhinaria arranged in a more or less regular row on segment III, with none on other segments.

Macrosiphum rudbeckiarum is monoecious on Rudbeckia species. It feeds on the undersides of the lower leaves of Rudbeckia spp. in cool shaded locations, and tends to be rather rare. The species is holocyclic, with oviparae and alate males in September. Macrosiphum rudbeckiarum is restricted to the western USA, especially the more interior mountains of Idaho and adjoining states.

 

Other aphids on the same host

Macrosiphum rudbeckiarum has been recorded on 3 Rudbeckia species (Rudbeckia amplexicaulis, Rudbeckia laciniata, Rudbeckia montana).

Acknowledgements

We are grateful to Andrew Jensen for making his images of Macrosiphum rudbeckiarum available for use under a creative commons licence.

We have used the species accounts given by Cockerell (1909), Hottes (1949) 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

  • Cockerell, T.D.A. (1903). Some Aphididae of the genus Nectarophora from New Mexico. Canadian Entomologist 35(6), 167-171 (p. 168) Full text

  • Hottes, F.C. (1949). Descriptions of some undescribed forms belonging to two little known species of the family Aphididae. Proceedings of the Biological Society of Washington 62, 45-52. (p. 47)

  • 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