I have now got a little further with the wasp identification, so here's a little update, with an updated version of the image.
The original micromoth larva is shown at point A, and is quite clearly chewed and dead. At point B we have the 'visitor', which has a distinctive dark gut. I have now discovered that the intruder is a Eulophid wasp, which is an ectoparasitoid of the micromoth larva.
So the sequence of events is as follows:
- Female micromoth lays her egg on the leaf.
- Egg hatches and the larva tunnels through the leaf, getting larger as it feeds, until reaching point A.
- Female Eulophid detects the moth larva inside the leaf and deposits her egg on or near the moth larva.
- Eulophid egg hatches and the wasp larva consumes the moth larva, leaving just the head capsule and other debris.
- Eulophid larva moves off back through the mine where it will pupate at point B.
I wonder if the wasp larva makes its little journey back down the mine in order to avoid being detected by a potential hyperparasitoid.
Anyway, here's the picture:
|Eulophid larva (B) having consumed Stigmella perpygmaeella larva (A)|