Identification & Distribution:
The adult apterae of Cavariella archangelicae are green or yellowish. Their antennae are 0.35-0.39 times the length of the body and the terminal process is1.5-2.0 times the base of the last antennal segment. Their siphunculi are more than twice as long as the cauda with the distal half somewhat swollen in a nearly symmetrical way. The supracaudal process has a broad basal part and is tongue-shaped about 0.7-1.0 times the length of the cauda. The body length of Cavariella archangelicae apterae is 1.5-2.6 mm.
The clarified slide mounts below are of adult viviparous female Cavariella archangelicae : wingless fundatrix, and winged.
Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.
The willow - angelica aphid host alternates from willow (Salix spp.) to angelica (Angelica). Sexual forms occur in October. The distribution of Cavariella archangelicae is cosmopolitan.
Keith Balmer 26/8/2014
I am contacting you at the suggestion of Alan Outen regarding an aggregation of aphids that I found on Angelica.
The attached photos were taken at Priory Country Park, Bedford (TL076496) on Sunday (24/08/14). The flower head was infested.
I looked up Angelica on your website http://influentialpoints.com and found a couple of candidate species. Cavariella archangelicae might be the best match, but I wasn't sure about the ID. (There is plenty of willow nearby).
Is it possible to identify the species from these photos please? I have specimens which I can pass on through Alan if a microscopic examination is desired.
Images copyright Keith Balmer, all rights reserved.
(For interest, Alan thinks that my finding of Macrosiphoniella millefolii a couple of weeks ago may be a county first kbalmer.blogspot.co.uk/2014/08/macrosiphoniella-millefolii.html).
Unfortunately we cannot provide a definite identification from the photos you sent us because the only aphids we can see in sufficient detail are 4th-instar nymphs with developing wing buds. Your first image (above) does have 2 bright green adults in its center but, despite our best efforts, we cannot resolve the crucial features.