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Aphis ceanothiCalifornia lilac aphidOn this page: Identification & Distribution Biology & Ecology Are these parasitized? Other aphids on the same hostIdentification & DistributionAdult apterae of Aphis ceanothi (see first two pictures below) are dull reddish or amber-brown, with dark siphunculi and cauda. The dorsal abdomen has large black antesiphuncular sclerites, often linked by a transverse sclerite on abdominal tergite VI (cf. Aphis boydstoni in north-west USA & Canada, which has the dorsal abdomen pale, without any presiphuncular sclerites). The antennal tubercles are weakly developed. The antennal terminal process is 1.5-2.8 times the length of the base of antennal segment VI. The length of the apical rostral segment (IV+V) is about the same as that of second hind tarsal segment. Marginal tubercles are small and only present on abdominal tergites I & VII (cf. Aphis boydstoni, which has the marginal tubercles broad, nearly flat and present on all of abdominal tergites I-VII). The siphunculi are slightly longer than antennal segment III, they are curved outwards, and are more or less cylindrical (cf. Illinoia ceanothi in western USA, which has very long and thin siphunculi, narrow in middle, with distal part dusky and somewhat swollen, narrowing again before the apex). The cauda is about as long as broad at base, and bears 3-4 hairs on each side. The body length of adult Aphis ceanothi apterae is 1.0-2.3 mm.
First & third images above, copyright Ken Schneider under a creative commons licence. Aphis ceanothi alatae (see third picture above) have secondary rhinaria convex, with narrow margins, arranged in double row on antennal segment III (distributed III: 11-36; IV: 0-5; V: 0-1). Marginal tubercles are quite large on the prothorax and abdominal tergites I and VII and, in some cases they are present on all abdominal segments. Immature Aphis ceanothi (see first picture below) are a pale orangey-brown when very young, but acquire the adult coloration in instar II-III.
First image above, copyright Alex Bairstow,
second image, copyright DLBowls, Aphis ceanothi is found on the flower stems and leaves of California lilac (Ceanothus spp.). In California it has also been found on Noltea africana (a South African tree). The species is monoecious holocyclic. Oviparae and apterous males have been found in September. It is sometimes attended by ants (see second picture above). Aphis ceanothi is distributed through western USA into Canada. Biology & EcologyAre these parasitized?The picture below shows a colony of aphids identified by the photographer as Aphis ceanothi. However, they lack the normal reddish-brown coloration, with most having the abdomen matt black.
Image above copyright Jesse Rorabaugh, public domain. The most likely reason for this is that they have been mummified by a braconid parasite, possibly an Aphelinus or Ephedrus species, both of which produce black mummies. Alternatively, the extent of dark shading of the abdomen may be variable in this species. Other aphids on the same hostAphis ceanothi has been recorded on 6 species of California lilac (Ceanothus cuneatus, Ceanothus integerrimus, Ceanothus obliganthus, Ceanothus sanguineus, Ceanothus thyrsiflorus, Ceanothus velutinus). On all but the last of these, it has been the only aphid species recorded. Blackman & Eastop list 3 species of aphid as feeding on California lilac (Ceanothus velutinus) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 0 as occurring in Britain (Show British list).
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