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Aphidinae : Macrosiphini : Illinoia ceanothus


Illinoia ceanothi

Ceanothus leaf aphid

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

Identification & Distribution

The fundatrix of Illinoia ceanothi (see first picture below) is green, with the antennae and legs progressively darker towards their apices, and the apical half of the siphunculi dusky. Subsequent apterous viviparae (see second picture below) are similar to the fundatrix, but have the siphunculi mainly pale, with only the apical quarter of the siphunculi dusky (cf. Aphis boydstoni & Aphis ceanothi, which have dark siphunculi). The antennae are about twice the body length, and have 0-3 small circular secondary rhinaria near the base of segment III. The hairs on antennal segment III (and on the abdomen) are very short, up to half the basal diameter of antennal segment III. The rostrum hardly reaches the third pair of coxae, and has the apical rostral segment 0.67 times the length of second hind tarsal segment, with 5-8 hairs plus 3 subapical pairs. The siphunculi are very slender, tapering slightly from base to beyond middle, and then somewhat swollen preapically; they are 2.2-3.1 times the caudal length (cf. the polyphagous Macrosiphum euphorbiae and Neomyzus circumflexus, which have their siphunculi less than 2.5 times the cauda). The cauda is pale or dusky, obtusely triangular, with 3 pairs of lateral hairs and one dorsoapical pair. The body length of adult Illinoia ceanothi apterae is 2.0-2.5 mm.

First image above copyright Andrew Jensen, second image above copyright Cedric Lee,
both under a creative commons licence.

The alate Illinoia ceanothi (not pictured) has 5-9 secondary rhinaria on the basal half of segment III. The wings have heavy venation, with a dark brown border along the pale pterostigma. The siphunculi have a reticulated zone at the apex with 2-6 rows of hexagonal cells.

Illinoia ceanothi feed on the leaves of California lilacs (Ceanothus spp.). The species is monoecious holocyclic, with oviparae and apterous males in late August to October. It is found in the western USA from California to Washington, and east to Idaho.


Other aphids on the same host

Illinoia ceanothi has been recorded on 2 species of California lilac (Ceanothus cordulatus, Ceanothus velutinus).


We are grateful to Andrew Jensen and Cedric Lee for making their images of Illinoia ceanothi available for use under a creative commons licence.

We have used the keys and species accounts of Bartholomew (1932) (as Amphorophora ceanothi) and Hille Ris Lambers (1966) (as Masonaphis ceanothi), 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


  • Bartholomew, P.S. (1932). Six new species of aphids with records of other species new to California. Annals of the Entomological Society of America 225, 713-729 (p717). Full text

  • Hille Ris Lambers, D. (1966). Notes on California aphids, with descriptions of new genera and new species. Hilgardia 97(15), 569-623. Abstract