One thing I love about sorting my trap samples is that I never know exactly what I’m going to see! Add to that the novelty of specimens from the far north, and the inherent diversity of insects, and it’s pretty much guaranteed that I’m going to see at least a few new-to-me species every time I sit down at my lab bench.
This term I’ve had an undergraduate student volunteer, Michael, working with me. He quickly demonstrated that he’s not only interested but also talented, progressing from sorting to pinning and pointing specimens (a task I’m notoriously anal about and rarely relinquish to others – everything must look *just so* – but Mike has proven up to the challenge) in a few weeks.
He’s also got what I’d call a “good eye”. While he may not know all the formal taxonomic names or anatomy of everything, he’s been quick to pick up on the visual cues and patterns of different groups of insects, and often points out interesting new things he finds in the samples he’s working on.
The other day, he looked up from his dissecting microscope and asked, “Do all wasps have wings?” He had been taught, you see, that two pairs of membranous wings was one of the defining characters of the wasps he was to extract from his samples. “This looks like a wasp, but it doesn’t have wings.” I came over to his station to take a peek and saw this:
A wingless female parasitoid wasp. Photo by Katie Sim (because I am useless at using our lab microscope camera and Katie can take great photos of tiny things like itsy-bitsy spider genitals. )
I saw that he had correctly nailed this critter as a Hymenopteran, and that, indeed, it had no signs of wings. In a moment of blinding genius, the first words that fell out of my mouth were: “It’s an ant!” Then, “No, wait…” Although the tiny, reddish, long-legged animal did rather resemble an ant, the abdomen, mouthparts and antennae were all wrong. A wingless wasp it was! How cool! I shared Mike’s excitement over the discovery, as this was a first for me as well.
I did some Googling and Bug Guide searching, and found that a number of parasitic wasp groups had wingless females. (I also read that many of these were ant-mimics that would sneakily attack ant-tended hoppers and their nymphs, so felt somewhat better about my earlier ID gaffe). Since there were too many possibilities, I called in the reinforcements: the post-doc in our lab also happens to be our resident wasp expert. Laura kindly agreed to take a look at the tiny critter and quickly confirmed her initial suspicions: it’s a member of the family Ichneumonidae, of the genus Gelis. And that’s about as good an ID as we’ll get, because apparently the Gelis sp. group is ridonculously difficult to pick through.
As far as their diet goes, Laura had this to say: “They attack a variety of things, generally things in silk cocoons. So, they can be hyperparasitoids on cocoons of Ichneumonoidea, or primary parasitoids on spider egg sacs or small Symphyta and Lepidoptera cocoons”. So much for my maybe-it-looks-like-an-ant-so-it-can-attack-ant-tended-hoppers theory. This wasp’s winglessness may therefore be a reflection of her preferred food sources: egg sacs or cocoons attached to low-lying vegetation are perhaps easier to access by land, rather than by air. By not “wasting” energy on the development of wings or on flight, the female wasp might be able to devote more energy to the production of her eggs and eventual offspring.
I love this little discovery in part because parasitoids are awesome and wingless parasitods are extra-cool. But I think I love it MORE because it involved the combined efforts of four people to pull all the pieces together (thanks Mike, Katie and Laura!)