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Plum - thistle aphidOn this page: Identification & Distribution Other aphids on the same host
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. The Brachycaudus cardui rostrum is long and reaches the hind coxae. 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. (cf. the short-haired Brachycaudus lateralis. for which the longest hairs on abdominal tergite 8 are 20-61 μm long, and the longest hairs on the hind femur are 10-25 μm long. ) Their siphunculi are black, thick and cylindrical and 1.7-3.4 times the length of their cauda. The body length of apterae is 1.8-2.4 mm.
The alate Brachycaudus cardui (see second picture above) has a large black patch on the dorsal abdomen. Immatures (see first picture below) are greenish or reddish. The second picture below shows a dorso-lateral view of an aptera in alcohol.
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.
Other aphids on same host:
Brachycaudus cardui has been recorded on at least 14 Prunus species, ans there are about 72 species of aphids which feed on plants in the genus Prunus worldwide (Show World list) of which 24 have been recorded in Britain (Show British list).