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Aphidinae : Macrosiphini : Illinoia spiraecola


Illinoia spiraecola

Varicoloured spirea aphid

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

Identification & Distribution

Apterae of Illinoia spiraecola are various hues of red, green and yellow (see first picture below of immature green aptera), often with a darker spinal stripe. The longest hairs on antennal segment III of the adult aptera are 0.30-0.45 times the basal diameter of that segment (cf. Illinoia spiraeae and Illinoia macgillivrayae, which have the longest hairs on antennal segment III 0.20-0.25 times the basal diameter). Antennal segment V is 1.8-2.4 times the length of the cauda (cf. Illinoia spiraeae and Illinoia macgillivrayae, which have antennal segment V 1.2-1.8 times the caudal length). The femora and tibiae are light brown and the tarsi black. The first tarsal segments have 3 hairs (cf. Illinoia spiraeae and Illinoia macgillivrayae, which have 4-5 hairs on the first tarsal segments). The siphunculi are light brown with a dark tip; they have subapical reticulation with several rows of closed polygonal cells, and are slightly swollen to 1.2 to 1.5 times their basal diameter on the distal third. The body length of adult Illinoia spiraecola apterae is 2.5-3.2 mm.

Note: The other Illinoia species that have been found on Spiraea species (namely Illinoia spiraeae and Illinoia macgillivrayae) only occur in the west of the USA and Canada.

Images above by permission, copyright Claude Pilon, all rights reserved.

Alatae and immature Illinoia spiraecola (see pictures above) are similarly coloured to the adult apterae. Most of our images show the green form, but some of the young nymphs in the picture below are of the yellow form.

Image above by permission, copyright Claude Pilon, all rights reserved.

Illinoia spiraecola feeds on a variety of meadowsweets (Spiraea spp.). There is no host alternation, and it is assumed that sexual forms develop in autumn. Patch (1914) describes finding several colour varieties of the species in Maine on Spiraea x vanhouttei, namely vermillion (scarlet), rose pink, bright green, yellow green, and lemon yellow. It is widely distributed in North America.


Other aphids on the same host

Illinoia spiraeae has been recorded on 4 species of Spiraea (Spiraea alba var latifolia, Spiraea salicifolia, Spiraea thunbergi, Spiraea x vanhouttei). The last of these was given in the earliest record by Patch (1914), but is not included by Blackman & Eastop.


We are grateful to Claude Pilon for pictures of Illinoia spiraecola in Canada (for more of her excellent pictures see).

We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Patch (1914) and MacGillivray (1958) along with Blackman & Eastop (1984) and Blackman & Eastop (2006) We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or 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


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

  • Patch, E.M. (1914). Maine aphids of the rose family. Bulletin of the Maine Agricultural Experiment Station 233, 253-280.