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Brachycaudus cardui

Plum - thistle aphid

On this page: Identification & Distribution 

Identification & Distribution:

Brachycaudus cardui apterae (see first picture below) are brownish-yellow, pale green or brown, with separate cross bars on thoracic segments, a large shining black spot situated dorsally on the abdomen and 2 or 3 black stripes at the tip. Their siphunculi are black, thick and cylindrical and 1.7-3.4 times the length of their cauda. The Brachycaudus cardui rostrum is long and reaches the hind coxae. The body length of apterae is 1.8-2.4 mm. Immature Brachycaudus cardui (see second picture below) often have reddish patches on a greenish background.

The longest hairs on abdominal tergite 8 are 85-110 μm long, and the longest hairs on the hind femur are 40-80 μm long. The length of these hairs distinguishes Brachycaudus cardui from the short-haired Brachycaudus lateralis

The clarified slide mounts below are of adult viviparous female Brachycaudus cardui : wingless, and winged.

Micrographs of clarified mounts  by permission of Roger Blackman, copyright AWP  all rights reserved.

In continental Europe Brachycaudus cardui host alternates between various Prunus species, mainly cherry, plum and apricot, and various wild and cultivated daisies (Asteraceae) especially thistle (Carduus and Cirsium spp.) and borage (Boraginaceae). In Britain it seems to live all year round on Asteraceae. Infested leaves undergo severe curling. Dense colonies occur at the base of flower heads and on the leaves. A return migration to primary hosts occurs in autumn. The plum-thistle aphid is found throughout Britain and Europe as well as in Asia, north Africa and North America.

Acknowledgements

Our particular thanks to Roger Blackman for images of his clarified slide mounts.

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 Blackman & Eastop (1994)  and Blackman & Eastop (2006)  supplemented with Blackman (1974) , Stroyan (1977) , Stroyan (1984) , Blackman & Eastop (1984) , Heie (1980-1995) , Dixon & Thieme (2007)  and Blackman (2010) . 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 

 

Identification requests

Alan Outen, 03 June 2014, Re: Aphid hunting

Today in Shefford, Beds I found a species on Oxford Ragwort (Senecio squalidus) but which was clearly not Aphis jacobaeae. Using the on-line Blackman and Eastop key it suggests four options: S. squalidus Brachycaudus cardui, helichrysi, lateralis; Macrosiphum euphorbiae, and I came down to Brachycaudus cardui, which I hope is correct.

Image(s) copyright Alan Outen,  all rights reserved.

   

Bob, InfluentialPoints:

  • Almost certainly Brachycaudus cardui. Can't distinguish B. lateralis from B. cardui in photos. B. lateralis is basically a short haired version of B. cardui. But looking at Blackman, they may be one and the same species, so for photos I'll just stick to B. cardui!

I have now looked at the hairs on the Brachycaudus under the stereo-binoc and these are certainly right for B. cardui.