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Masked yarrow aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host
Identification & Distribution
Adult apterae of Macrosiphoniella usquertensis are brownish with a thick coating of greyish wax except for clearly defined patches on the mid-dorsum and around the bases of the siphunculi - remarkably similar to the wax pattern of Macrosiphoniella subterranea on ox-eye daisy. The third antennal segment is mostly pale, and has 2-11 secondary rhinaria (cf. Macrosiphoniella subterranea which has 10-22 secondary rhinaria on antennal segment III). The legs and antennae of Macrosiphoniella usquertensis have contrasting pale and black sections. The siphunculi and cauda are black, and the siphunculi are 0.8 -1.0 times the length of the cauda (cf. Macrosiphoniella subterranea the siphunculi of which are 0.9-1.15 times the length of the cauda).
The alate Macrosiphoniella usquertensis (see second picture above) lacks the large wax-free patch on the mid-dorsum, but is wax free around the bases of the siphunculi. It has 20-35 secondary rhinaria on antennal segment III, and the siphunculi are similar in length to or slightly shorter than the cauda (cf. Macrosiphoniella subterranea the siphunculi of which are usually longer than the cauda). Oviparae are reddish, and males are alate.
Macrosiphoniella usquertensis feeds on yarrow (Achillea millefolium) and other Achillea species, and occasionally field wormwood (Artemisia campestris). It is mainly found near the tips of the lower leaves, and feeding results in premature senescence of the leaves. Oviparae and alate males develop in autumn. The masked yarrow aphid is found throughout Europe, and has been recorded in Canada.
Biology & Ecology
Feeding by Macrosiphoniella usquertensis appears to be toxic to its host, yarrow. Aphids feed particularly near the tips which causes the tips to turn brownish and wither (see picture below).
The aphids continue to feed even on very senesced leaves (along with, on this occasion, a lone Macrosiphum euphorbiae visible top-right below).
Blackman (2010) reports that oviparae and alate males occur in northwest Europe in late August-October. We have found sexuales in populations of Macrosiphoniella usquertensis in southern England as late as 30th November (see picture below).
The picture above shows (from left to right) an immature (or brachypterous) male and a mature ovipara.
Other aphids on same host:
Macrosiphoniella usquertensis has been recorded from 12 Achillea species.
Blackman & Eastop list 46 species of aphid as feeding on yarrow (Achillea millefolium) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 26 as occurring in Britain (Show British list).