Still plenty of invertebrates around, look for leafmines!

neilmoths's picture

I had the pleasure of leading a field trip last week looking for leafmines.  Well I say that I led it, what that really means is that I told people where to meet up and spent a few hours in the company of some very knowledgeable people looking at leafmines.  This was the fourth Buckinghamshire Invertebrate Group leafmining field trip and was held at Salcey Forest on the Bucks/Northants border with the Northants Moth Group. 

So far, the list for the day is 65 species, 46 of which were leafmines, the rest comprising a few galls, adult and larval intertebrates.

Leafmines provide a way of finding many otherwise difficult to find species, as the adults are very rarely found, and even when they are can be very hard to indentify.  The species are also often very under-recorded so provide very valuable records.  There are some excellent online resources to help indentify leafmines.

Despite having been interested in leafmines for some years, I still managed to record four new species, two of which are significant county records, both Notable b.  First Ectoedemia rubivora which occurs on Rubus fruticosus agg. (Bramble).  Ectoedemia rubivora

We had two scarce species on Rosa, Emmetia angusticolella and the Nb species Emmetia angusticollella.

Emmetia angusticollella  

Also very nice to find on Rosa was a case-bearing larva of Coleophora gryphipennella, only the second time I'd recorded this species, but we saw several larvae.

Coleophora gryphipennella

A few other things we found, or at least the few I took photographs of!  Euthrix potatoria (Drinker)  and Psyche casta larva

Euthrix potatoria (Drinker) Psyche casta

A mine on Urtica dioica (Common Nettle) which I think can only be Agromyza anthracina because of the threads of frass.

Agromyza anthracina Agromyza anthracina

Overall a great day with lots to see and lots to think about.  I'd recommend leafmines to anyone interested in extending their moth list or looking for a new avenue of exploration!




Leafmining Websites

Love leafmines - I just can't stop myself from looking for them wherever I go! I blame my misspent youth... ...I did an awful lot of fieldwork for the Smaller Moths of Surrey and spent many days searching for leafmines. My only regret is ignoring the many non-lepidopterous mines I encountered as they were irrelevent to my 'quest'. Clearly I wasn't PSL enough back then! There are many micro-moths on my list that I've ONLY seen in the larval stage. As Neil rightly mentions, many species are far more readliy identifiable by their mines than as adults. Well worth getting into if you get a chance. Many are hostplant specific and have highly diagnostic mines so you'll be able to name at least a few with ease. A lot of it is down to detective work and there are some really good websites out there to help you along.

Important things to note that will help you reach a correct determination - you really do need to have a good idea of the hostplant. This is probably the single biggest aid to identifying the insect causing the leafmine. Secondly - check the frass! Is it linear, is it made up of a row of dots/sweeping back and forth through the mine/stuck to the upperside of the mine in patches/completely absent? Yep, different species poo in different ways - even within a genus! Is the mine a linear track, snaking its way across the leaf? Is it a blotch or a blister? Has it caused parts of the leaf to discolour? Is it on the upperside or underside of the leaf? Does it cross the midrib or veins? Does it start at the edge of a leaf, in the centre, in the petiole or on a twig? Are there more than one larva within a single mine? Does the larva have visible legs or spiracles, and what colour are the head and the body? Can you see the gut, if so what colour is it? Be aware that mines aren't just restricted to leaves, a few also occur on the surface of twigs, in the samara or on the surface of the fruit. There are some really excellent websites dedicated to leafmines. Best of the bunch are probably British Leafminers, The leaf and stem mines of British Flies and Leafminers and plant galls of Europe - but each of those have a page of Links to related sites. The last site deals with plant galls...but that's yet another kettle of fish to get to grips with - and they are every bit as enjoyable and ubiquitous :)