Identification & Distribution:
Macrosiphum euphorbiellum adult apterae (see first picture below) are usually green, sometimes with a darker green longitudinal stripe, but may also be pink, magenta or wine red. Their eyes are reddish and the antennae are dusky. The antennal terminal process is 4.2-5.2 times longer than the base of the sixth antennal segment. The apical parts of the femora are black (cf. Macrosiphum euphorbiae which has the apical parts of the femora pale or only slightly dusky). The siphunculi are pale with the tips darker. The cauda is rather pointed and not constricted. The body length of Macrosiphum euphorbiellum apterae is 2.0-4.0 mm.
The alate (see second picture above) is similarly coloured to the aptera. The micrograph below shows an adult Macrosiphum euphorbiellum aptera in ethanol.
The clarified slide mounts below are of adult viviparous female Macrosiphum euphorbiellum: wingless, and winged.
Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.
The euphorbia aphid does not host alternate, but spends its entire life cycle on spurge, especially wood spurge (Euphorbia amygdaloides) and red spurge (Euphorbia characias). It feeds on the stems and in the flowerheads. Red oviparous females and red winged males have been found in autumn in Switzerland. Macrosiphum euphorbiellum is found in southern England, southern Ireland and much of central and southern Europe.
Other aphids on same host:
Macrosiphum euphorbiellum have been recorded from 4 Euphorbia species (Euphorbia amygdaloides, Euphorbia characias, Euphorbia esula, Euphorbia semiperfoliata).
- Blackman & Eastop list 4 species of aphid as feeding on wood spurge (Euphorbia amygdaloides) worldwide. Of those aphid species, Baker (2015) lists 2 as occurring in Britain:
Macrosiphum euphorbiae
and
Macrosiphum euphorbiellum.
- Blackman & Eastop list 6 species of aphid as feeding on red spurge (Euphorbia characias) worldwide. Of those aphid species, Baker (2015) lists 3 as occurring in Britain:
Aphis euphorbiae,
Macrosiphum euphorbiae
and
Macrosiphum euphorbiellum.
Acknowledgements
Our particular thanks to Roger Blackman for images of his clarified slide mounts.
Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made 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).
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