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Aphidinae : Macrosiphini : Illinoia maxima
 

 

Illinoia maxima

Green-striped thimbleberry aphid

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

Identification & Distribution

Adult apterae of Illinoia maxima (see first picture below) are whitish green with a slightly darker green dorsal midline, and mainly dusky siphunculi. The antennae are pale, but with the apices of the segments and segment VI darker. The antennal terminal process is 4.5-6.2 times the base of segment VI (cf. Illinoia rubicola, which has the terminal process 5.5-8.2 times the base of that segment). Antennal segment III has 7-14 secondary rhinaria in a row over the basal 0.5-0.55. The longest hairs on antennal segment III are 0.67-0.88 times the basal diameter of that segment. The rostrum reaches to the hind coxae, with the apical segment (RIV+V) about 1.6-1.7 times as long as the second hind tarsal segment (HTII) (cf. Illinoia davidsoni, which has RIV+V 1.9-2.2 times HTII). There are rather prominent, often raspberry-like marginal tubercles on the prothorax and abdominal tergites II-V, those on the prothorax and tergite V being the largest (cf. Illinoia davidsoni, which has marginal tubercles very small or absent; and cf. Illinoia rubicola, which has marginal tubercles present on all of tergites I-VII). ). The legs are pale, with the apices of tibiae and the tarsi darker. The siphunculi are dusky with darker apices and a pale base; they are swollen on the distal third, and the apical part is reticulated (cf. Amphorophora parviflori and other Amphorophora spp., which do not have the siphunculi reticulated). The cauda is pale, with 8-11 hairs. The body length of adult Illinoia maxima apterae is 2.9-3.9 mm long.

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

Alate Illinoia maxima (see second picture above) have a dark pterostigma and a dark spot at tip of forewing. They resemble the apterae, but with a rather dark head, a partly pigmented pronotum, and the rest of the thorax mostly dark. Antennal segment III has 12-24 secondary rhinaria in an irregular row on the basal 0.67-0.80 part. Marginal tubercles are present as in apterae, with those on tergites II-IV at the caudal margin of small brownish marginal sclerites. Wing venation is normal with darkened veins; the forewings have a long, black stigma, and a large dark spot on the tip (cf. Illinoia davidsoni, which has no dark spot on the tip). The siphunculi are light brown to black throughout, reticulated on the distal 10%.

Both images above copyright Jesse Rorabaugh, no rights reserved.

Illinoia maxima is monoecious on leaves of thimbleberry (Rubus parviflorus). The species is holocyclic, but with an 'abbreviated life cycle' (sexual forms are produced in the 3rd or 4th generation in late spring or summer). The biology is described by Frazer & Forbes (1968). The green-striped thimbleberry aphid is found in the moist parts of northwestern North America.

 

Other aphids on the same host

Blackman & Eastop list 6 species of aphid as feeding on thimbleberry (Rubus parviflorus) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 15 as occurring in Britain (Show British list).

Acknowledgements

We are grateful to Andrew Jensen and Jesse Rorabaugh for making their images of Illinoia maxima available for use under a creative commons licence, and in public domain respectively.

We have used the keys and species accounts of Mason (1925) (as Amphorophora maxima) and MacGillivray (1958) (as Masonaphis maxima), 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

  • Frazer, B.D. & Forbes, A.R. (1968). Masonaphis maxima (Mason) (Homoptera: Aphididae), an aphid on thimbleberry with an unusual life history. Journal of the Entomological Society of British Columbia 65, 36-39. Full text

  • MacGillivray, M.E. (1958). A study of the genus Masonaphis Hille Ris Lambers, 1939 (Homoptera, Aphididae). Temminckia 10, 1-131 (p. 36.)

  • Mason, P.W. (1925). A revision of the insects of the aphid genus Amphorophora. Proceedings of the United States National Museum 67(20), 1-92. Full text