Worcestershire Record No. 6 April 1999 p. 24

LEAF MINING LEPIDOPTERA

These notes were circulated at the Annual BRC Meeting . Prospective searchers for leaf mines should find them useful.

If you find leaves with mines Dr Simpson would be pleased to identify them and you may post them to him at Sycamores, Old Rectory Gardens, Leigh, Worcs., WR6 5DL. Please note date of finding and exact place found - preferably grid reference - and identity of plant if possible.

Many leaf mines are made by moths whose small larvae feed actually within the substance of a leaf. As they feed and grow they leave a 'mine' in the form of a blotch or track which is often characteristic of the species involved. The nature of the mine and identity of the foodplant, and sometimes the colour or form of the larva, usually enable the species to be identified. About 160 species of leaf mining moths occur in Worcestershire and a large number of other microlepidoptera start life in their early instars by mining before feeding externally as they grow larger. Species of flies, beetles, and sawflies also feed in leaf mines. In April and early May mines of a primitive family of moths, the Eriocraniidae, occur commonly in leaves of Birch, Oak, and Hazel. The frass ( faeces ) is in the form of long narrow threads, which enables them to be distinguished from sawfly larvae which also occur in leaves of Birch and Oak. There are a few leaf miners in a large number of other families but the two largest families of leaf miners are the Nepticulidae, which are tiny metallic moths whose larvae make tracks and blotches in many trees and shrubs and some herbaceous plants, and the Lithocolletinae, whose larvae make inflated mines in the leaves of many trees, pupating within their mine.

One of these, Phyllonoryter leucographella is a recent colonist. It was first noticed feeding in garden Pyracantha in Essex in 1989 and reached Worcs. in 1996. I would be pleased to have any records from around the county although I expect it to be widespread by now.

Another family called the Coleophoridae have larvae which live in cases made of pieces of the foodplant or from silk, which they transport about like case-bearing caddis larvae, then attach it to the leaf and use it as a protective retreat as they mine into the substance of the leaf, leaving characteristic blotches with a small hole on the underside of the leaf. About 40 leaf miners of this family occur in the county.

The best way to get into leaf miners is to buy 'A Field Guide to the Smaller Lepidoptera' by A.M.Emmet, or Vols 1-3 of 'Moths of Great Britain and Ireland' if you can afford them.