Since the beginning of March, the signs of spring have been trickling in: arrival of turkey vultures and red-winged blackbirds; migration of blue-spotted salamanders on the first rainy night; skunk cabbage blooming; various insects and spiders becoming active again. This week another milestone was reached: I checked my assorted bags and jars of overwintering galls and leaf mines, and I found something moving around in one of the bags:
Isn’t she a cutie? This 3 mm wasp is a member of the genus Ormyrus, which includes 16 described species in North America, all of which are parasitoids of gall wasps, as far as is known. She emerged from the little reddish gall in the photo below (if you look closely you can see the exit hole).
I collected these galls in February, suspecting that at least the smaller one was parasitized. Normal “round bullet galls” look more like the one on the right, though even this is smaller than a typical one. Like the vast majority of galls on oaks, they are caused by wasps in the family Cynipidae. This particular gall is caused by Disholcaspis quercusglobulus, and apparently the unparasitized adults emerge from their galls in October. Since I brought these galls inside, this isn’t necessarily the time that the Ormyrus parasitoids are supposed to emerge (in fact, I had one emerge from the same type of gall in May of 2005), but nevertheless the appearance of this wasp is a sign that I need to start checking every day if I want to find my emerging insects while they’re still alive. Stay tuned for the next arrival…
Thanks to Ross Hill and Bob Carlson for identifying this wasp.