The recording of these leaf-mining lepidoptera is increasingly popular and has
been of personal interest for several years.Some
of our smallest moths, only a few millimetres in wingspan, feed as larvae
inside leaves. The results of this feeding, termed leaf mines, can be visible
from the outside of the leaf and are of use in moth recording. Most
leaf-mining moths tend to be specific in their host plant requirements,
presumably as they are living in very close association with their food. The
food plant that the mine occurs in, the pattern of feeding and the way frass
(caterpillar excreta) has been laid down in the mine, as well as other
features, allows the identification of the majority of these very small moths.
The recording of these leaf-mining lepidoptera is increasingly popular and has
been of personal interest for several years.
In September 2002 Jon Clifton and myself were carrying out some leaf-miner recording in the Mildenhall area. We found some leaf-mines in fallen poplar leaves where the mine started in the petiole of the leaf and proceeded up the petiole as a narrow track to the base of the leaf where it expanded into a blotch in the lamina of the leaf. On consulting the identification keys we found only one species that fed on poplar in this way - Ectoedemia turbidella. The key was specific about E. turbidella feeding on grey poplar but this was rashly passed over at the time and we recorded the species as E. turbidella. After mentioning our findings to Neil Sherman he also found similar mines on poplar leaves at a site near Ipswich.
On
sending the records to the national micro-lepidoptera recorder I was informed that
E. turbidella has only ever been found feeding on grey poplar in this
country and that the leaves in which we had found mines did not appear to be
grey poplar. Further investigation showed that the mines we had found were in
fact in Italian poplar leaves. The question then arose as to what species had
formed these mines. 
As the mine was very similar to other leaf-mining moth
species we were convinced that this mine must have been produced by something lepidopterous.
This left us with two possibilities, either E. turbidella occurring
on a previously unknown food plant or some unknown species of leaf miner. I
consulted some European literature on this family, which revealed that there is
a European species, Ectoedemia hannoverella that feeds on black poplar
and its hybrids, including Italian poplar.
The solution to this moth’s identity would require rearing through of adults from mines collected in the autumn. If we were able to rear through some adults then their identity could be determined by dissection, as E. hannoverella and E. turbidella are indistinguishable in the majority of cases as adults from external appearance alone.
This group of moths has a reputation for being tricky to rear through to the adult stage as the larvae leave the mine and spend the winter as a pupa in a small cocoon, with the adults emerging in the spring. Being so small they are prone to drying out and appear to need exposure to cold weather before they will emerge. Also some species can be very heavily parasitised. Jon Clifton, Neil Sherman and myself took mines from two sites in Suffolk and tried different techniques to over-winter them in the hope that at least one of us would manage to rear some adults. This actually proved more successful than expected and in April and May the majority of adults hatched from both sites. These were determined by Jon Clifton to be E. hannoverella - a new species of moth to Britain found in Suffolk.
Returning to events in late 2003, I had continued to search for further sites with mines in black poplar hybrids and managed to locate two further sites in Suffolk, one in the Woodbridge area and the other near Brandon. Andy Musgrove also managed to find some mines in Norfolk at Thetford. It would appear that E. hannoverella is established in at least two broad areas of Suffolk and I suspect will be found in other areas of the county as well. How widespread it will be outside the county is hard to say. Leaf-miner recording certainly has a long history in Essex and some of the other adjoining or nearby counties to Suffolk have or have had recorders interested in recording leaf-mining moths. Black poplar and its hybrids have other leaf-mining moth species associated with them that are likely to have attracted the attention of leaf-miner recorders in the past, so it would seem unlikely that they have been over-looked for a long period of time. Now that the species has been recognised as occurring in this country it will hopefully encourage other recorders to look for it so that its precise distribution can be determined.
Tony Prichard
3 Powling Road
Ipswich
Suffolk
IP3
9JR
email: tony.prichard@btinternet.com
© 2004 Suffolk Naturalists' Society
used by kind permision.