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21 July 2016

21 July 2016 – Very Small

Elachista atricomella

A trap earlier this week welcomed a new wave of moths, many of which I was seeing for the first time: Swallow-tailed Moth, Small Fan-footed Wave, a plume moth yet to be verified, a Parornix sp., and a new species confirmed by Dave Chesmore: Elachista atricomella.

Inconspicuous as it is, we still managed to spot it wrapping its wings around the whole of its trunk and limbs, lying almost flat against the eggbox like a beached seal. It has one of those neat labial palps that curve up around its face, and the entire forewing is covered in mottled grey. A white fascia is found at one-half and is interrupted in the middle by the ground color. A triangular white patch marks the angle of the tornus and from there diffuses down to the apex.

Elachistos means very small, and atricomella may be split into ater, meaning ‘black’, and coma, ‘the hair of the head’, although the second part may be a misnomer because for it to be the correct species the hair on the apex of the head should be brown, not black. The closest illustration I can find is under the name Microsetia exiguella, though here again the moth is described as having a black head.

Elachista atricomella (Illustration)

When the larva feeds, it makes a narrow white mine and moves from one leaf to another as it grows. One of its foodplants is the cock’s-foot grass (Dactylis glomerata).

Post: Tung Chau (UPenn)