Miner Matters:                                                                                     November 2003

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Thanks for the replies on the mines in the last newsletter. There was general agreement that they were Stigmella species and some would leave it there, due to the difficulty in identifying these mines purely on the basis of an unoccupied mine. It is recommended that the larva is bred through.

All who attempted identification agreed that the first mine was Stigmella samiatella, whereas the second mine brought a more mixed response, with the majority opting for a possible S.samiatella again.

The first photo seems to show a frass pattern which matches the description in Johansson, in that it is a long twisting gallery with very noticeable dark frass, in a broad line, with some frass in arcs. The final feature he mentions is the thin last section of the frass. He does say that the mine is not separated with much certainty from S.atricapitella and S.ruficapitella.

Perhaps you have other ways of separating this group of Oak (Quercus) /Sweet Chestnut (Castanea) miners?

New leafmine discussion group

Tony Pritchard has now set up a discussion group devoted to the study of leaf miners at: http://groups.yahoo.com/group/ukleafminers/

Please send me an email if you wish to join this group and I will arrange for an invitation to be sent to you.

Oak Phyllonorycters   

Jon Clifton found that rearing through apparent autumn Phyllonorycter quercifoilella mines gave him some Phyllonorycter messaniella instead! A finding echoed by David Manning as he had found that every small mine with U-shaped frass (where not parasitised) contained a pupa or pupal exuvia of P.messaniella.

It would seem that the identification of these mines needs re-examining. Colin Plant  immediately retrieved all the oak leaves from his compost heap, some of which have been there for a while, brought them indoors and separated out the 'probably' quercifoliella mines. Of the 11 adults that emerged initially in the warmth of his study, 5 were messaniella and 6 were quercifoliella. He is fairly sure all were named from the mines as quercifoliella (though it is hard to be sure with retrieved samples from the compost heap). There was no difference in the frass pattern between the two mines when held up to the light - both cocoons appeared to rest in a U-shaped frass arrangement.
However, those that yielded quercifoliella had the cocoon adhered very firmly to an uneaten patch of green on the upper leaf epidermis. Those
yielding messaniella had no uneaten parenchyma at all and were only rather loosely attached to the upper epidermis.

If you want to see if this is a reliable method of separating these - Colin's method is to kept them warm and damp in a sandwich box in the kitchen after rescuing them from the (warm) compost heap! If you want to try and keep them for spring emergence then place the mines inside a pair of tights (or pop sox!) and anchor them outside to a shrub etc. Bring inside next spring for emergence.

A reference for the mines of Phyllonorycter species is provided by Willem Ellis : 'Gregor F & Patocka J, 2001. Die Puppen der mitteleuropäischen Lithocolletinae. - Mitteilungen des internationalen entomologischen Vereins, Supplement 8: 1-186'. The text is in German, but with lots of photos!

New Diptera species

A new British Diptera (Agromyzidae) species - Cerodontha sylvatica has been discovered by David Gibbs mining Luzula sylvatica (Greater Wood-Rush) in South Gloucestershire (Dipterists Digest - Vol10 No1, 2003). It makes linear mines in the leaves of this plant.

Horse Chestnut miner spreads

This miner, Cameraria ohridella, has started to spread rapidly throughout Southern England with reports from Oxford, Buckinghamshire, Kent and  London Boroughs down to West Byfleet in Surrey during 2003. It seems as if its rapid spread is mirroring that in Europe.

Newsletter of leafmines.co.uk                                                                                                                                             November 2003