Aphis praeterita

Identification & Distribution:

Adult Aphis praeterita apterae are lemon yellow to greenish yellow (see first picture below), sometimes mottled with darker green (see second picture below), and with no wax stripes. Their abdominal dorsum is membranous with little or no sclerotization. Marginal tubercles are small (barely visible in the micrograph below right), those on tergites 1 and 7 being distinctly smaller than the adjacent spiracular plates. The tapering siphunculi are apically dusky and have regular imbrication. They are 1.29-1.95 times the caudal length. The cauda is slightly dusky and finger-shaped. The body length of adult Aphis praeterita apterae is 1.44-2.47 mm.

Alates (not pictured) have short cross bars or sclerites on the posterior abdominal tergites, and frequently also on some of the anterior 5 tergites. Antennal segment III has 7-12 secondary rhinaria, IV has 0-5 and V has 0-1.

The hairy willowherb aphid does not host alternate, remaining all year on the same host, hairy willowherb (Epilobium hirsutum). They feed on the underside of the leaves and on the growing shoot apices. These aphids are not usually ant attended. In Britain, Aphis praeterita has been recorded in most southern English counties. It is widely distributed in Europe, Central Asia, Pakistan and China - and has been introduced to North America.

Biology & Ecology

Aphis praeterita normally feed on the young leaves and new shoots of their host, usually Epilobium hirsutum (see picture below).

Perhaps surprisingly we have also found them on the woody underground stem of Epilobium (see picture below).

The aphids were not attended by ants either above or below ground, and as a result there were numerous predators and parasitoids attacking the colonies.

The first image above shows a cecidomyiid larva predating an immature aphid, whilst the second shows a parasitoid mummy.

Other aphids on same host:

Aphis praeterita has been recorded from 9 Epilobium species, plus one or more unknown Oenothera species.

Blackman & Eastop list 11 species of aphid as feeding on hairy willowherb (Epilobium hirsutum) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 10 as occurring in Britain (Show British list).

Acknowledgements 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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