I’ve now made it up to the end of March in my photo sorting, and just came across some photos I took of something that emerged from a leaf mine collected last November.
This is the mine of a Stigmella species (Nepticulidae) in a red oak leaf (just under 1 cm across), and since there are a number of oak-mining Stigmella species, it is necessary to raise the larva to an adult moth to figure out which species it is. As shown here, nepticulid larvae exit their mines to spin cocoons, and they finish feeding so quickly that I don’t often find mines with the larvae still inside. So when I found this oak mine and saw the larva still there (in the center of the wide end, beyond the frass trail), I of course collected it to see if I could get an adult. The larva had still not emerged when I moved all my bug containers outside for the winter, so I figured something was wrong, but I decided not to throw the leaf away just yet. On March 28, an exit hole had been chewed…
…and this boldly colored little wasp (1.6 mm) had emerged:
I believe this is a eulophid wasp in the genus Zagrammosoma. Based on the Universal Chalcidoidea Database, this may be the first record of a Zagrammosoma parasitizing a Stigmella. My only other encounter with one of these wasps was last fall, when I was cleaning out containers, and in addition to finding what seems to be the first record of Dienerella pilifera for this side of the world, I found this dead wasp in the vial containing leaf mines of Orchestes mixtus collected in Ohio in the spring. In addition to being the first rearing record of O. mixtus from musclewood, that seems to be the first record of a Zagrammosoma parasitizing a weevil of any kind. I wonder how long I’ll have to study leafminers before I stop finding new things everywhere I look.
[Added 6/13/2013:] Christer Hansson has examined this wasp and determined that it is a species of Cirrospilus, not Zagrammosoma. Cirrospilus species have, in fact, been reared from Stigmella species before.