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"It has long been an axiom of mine that the little things are infinitely the most important" (Sherlock Holmes)

 

 

Identification & Distribution

Adult apterae of Aphis serpylli are rather dark blue-green, with a very slight wax bloom (see first two pictures below). The dorsal abdominal sclerotic pattern is usually limited to bands across tergites 7-8, but is lost in small individuals. Marginal tubercles are present on abdominal tergites 1 & 7, but not on tergites 2-6. Hairs on the legs are mostly rather short, but caudal hairs are long. The siphunculi have a marked flange and are 0.54-1.33 times as long as the cauda. The adult apterae are small with a body length of only 1.00-1.38 mm.

Alate Aphis serpylli (not pictured) have marginal and postsiphuncular sclerites, which are often rather pale and inconspicuous, and bands on tergites 6-8 or 7-8. The micrographs below show dorsal and ventral views of an adult apterous Aphis serpylli.

Aphis serpylli does not host alternate, but is monoecious on thyme. It produces sexual forms. The males are wingless. Aphis serpylli feeds on the shoots and inflorescences of Thymus species, and certain on other members of the Lamiaceae (the mint family): Micromeria (a genus which includes White-leaved Savory) and Thymbra (a genus which includes Mediterranean thyme). Aphis serpylli is ant attended, which sometimes tent-over the colony. Aphis serpylli occurs in Europe, the Middle East and Central Asia - albeit seldom recorded.

 

Biology & Ecology

We have only found Aphis serpylli once - in the yard of a house up for sale in East Sussex. Thyme that had been planted in a herb garden had spread in between paving stones, apparently providing ideal conditions for this small inconspicuous species.

A thriving population of Aphis serpylli was found on the plants growing between the paving stones.

The aphids were attended by black garden ants (Lasius niger) which had tented the aphids with soil particles and dead leaves.

As soon as the new owners occupied their house, they pressure-washed the thyme neatly out of existence.

 

Other aphids on same host:

Blackman & Eastop list 8 species of aphid  as feeding on Thyme (Thymus species) worldwide, and provide formal identification keys.

Of those aphid species, Baker (2015)  lists 7 as occurring in Britain: Aphis serpylli, Aulacorthum solani,  Eucarazzia elegans, Kaltenbachiella pallida,  Myzus ascalonicus,  Myzus ornatus  and Myzus persicae. 

There are 3 species on Thymus serpyllum (wild thyme, creeping thyme), all of which occur in Britain: Aphis serpylli, Eucarazzia elegans & Kaltenbachiella pallida.  On Thymus vulgaris (common thyme, English thyme, summer thyme, winter thyme, French thyme, or garden thyme) there is just one species: Aphis serpylli.

Acknowledgements

We have made provisional 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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