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Aphis lugentisAmerican ragwort aphidOn this page: Identification & Distribution Other aphids on the same hostIdentification & DistributionAdult apterae of Aphis lugentis are dull blackish green to dark olive, or dark yellow-brown with a greenish tinge, with entirely dark appendages, often marked with sclerotic bands on tergites VII & VIII. There are 1-11 secondary rhinaria on antennal segment III, 7-11 on segment IV and 0-2 on segment V. The antennal terminal process is usually 1.6-2.1 times the base of antennal segment VI (cf. Aphis senecionis in mid-west USA, which has the terminal processs 1.35-1.55 times the base of that segment). The antennal hairs are pointed, 0.7-1.1 times as long as the basal diameter of antennal segment III. Marginal tubercles are only present on abdominal tergites I & VII (cf. Aphis jacobaea in Europe, and Aphis senecioradicis in western USA, which regularly have marginal tubercles present on tergites II-IV). The tibiae are entirely dark. The siphunculi are cylindrical, with flanges and imbrication, and are generally 1.2-1.5 times the caudal length. The cauda is elongated, nearly parallel-sided, with a tendency to constriction near its base. The cauda bears 6 or 7 hairs on either side, and is broadly rounded at the apex (cf. Aphis senecionis which has a cauda which tapers to an almost pointed apex). The body length of adult Aphis lugentis apterae is 2.0-2.8 mm.
First image above copyright Chieffo, second image copyright Krasik, Aphis lugentis alatae (for clarified mount see picture below) have the head and thorax black and the abdomen blackish-green. Secondary rhinaria on the antennae are round, medium in size, scattered along the entire length of the segments, there are 19-24 on segment III, 7-11 on IV and none on V. There are marginal tubercles present, especially on tergites I and VII. Oviparae have the hind tibiae distinctly swollen and thickly covered along almost their entire length with moderately large, round, flat rhinaria. Males are usually alate, but occasionally apterous, with rhinaria on antennal segments III, IV and V.
Image above copyright CBG Photography Group under a Creative Commons License. Aphis lugentis is found on the leaves, stems and roots of several Senecio and Erigeron species, where it can form dense colonies. It is is often attended by ants (see picture above), much like the the similar European ragwort aphid Aphis jacobaeae. Populations are holocyclic, with oviparae and alate males in autumn. The species is native to the USA (except the north-east), Mexico and western Canada. It has proved to be invasive in recent years, having been found in South America, in southern France and Tunisia and in Australia. In Argentina Aphis lugentis has been found colonising some endemic Asteraceae, and has also been observed to be displacing native Senecio-feeding Aphis species. Other aphids on the same hostAphis lugentis has been recorded on 19 Senecio species (Senecio atratus, Senecio aureus, Senecio canus, Senecio filaginoides, Senecio gallicus, Senecio giliesii, Senecio glabellus, Senecio hydrophilus, Senecio integrifolius, Senecio jacobaea, Senecio leucostachys, Senecio lugens, Senecio plattensis, Senecio scopulinus, Senecio serra, Senecio spartioides, Senecio subulatus, Senecio subumbellatus, Senecio triangularis).
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