Learning to identify a species — connecting its characteristics with the often arbitrary name humans have assigned it — is a gratifying first step. But it’s an incomplete step, in the same way that being introduced to other people differs from actually getting to know them. What do they do? What things matter to them? What is their life history?
Happily for contemporary naturalists, it is increasingly easy to get help with both identifying and understanding wild plants and animals. Print and electronic sources are proliferating while growing in accuracy and reliability. But there is still a huge difference between reading about a species and truly knowing it.
To take an example, for years now I’ve had a nodding acquaintance with blister beetles of the genus Meloe. While individual species are hard to distinguish, learning the genus as a whole was easy: These are large, leathery beetles, about an inch long, glossy black, with hugely distended abdomens and tiny, vestigial wings.
Basic information about them is readily available. Like all blister beetles, they exude a caustic, yellowish juice from their joints when they’re irritated (hence their name). Adults are herbivorous, and the youngsters are parasites on other insects, especially ground-nesting bees. But until recently, I’ve encountered Meloe infrequently and in small numbers; typically I find one or two adults per season, usually in early spring in Correllus State Forest. This is a thin basis for acquaintance!
This past weekend, however, I hit the jackpot, observing more than 60 of these beetles as they applied themselves conscientiously to the reproductive part of their life cycle. I still can’t tell which species I’m finding, but with this first-hand immersion in the lives of these insects, I finally feel like I’m getting to know them.
For one thing, I had no idea that mating was such a social activity for Meloe. The individuals I recently found were all participants in mating aggregations, ranging from about 10 to more than 30 individuals, clearly associating with one another over an area perhaps 10 feet across. There’s really no way to describe these groups other than as blister beetle sex orgies: Single beetles and pairs in various stages of courting and mating were intermingled, with single males watching mating pairs closely and occasionally trying to cut in on the action.
And courtship, specifically, was fascinating to watch. Males and females approach other, interweaving their long antennae and rubbing their faces together almost as if kissing. As with most other insects, actually mating occurs with the male perched precariously on top of the female; a critical part of this process involves mutual antenna-rubbing, which looks both urgent and almost tender (if one can use that term with bugs!) at the same time. The male’s goal, it appears, is to catch the female’s antennae in distinctive little kinks in the male’s own antennae (these kinks are obvious, and the easiest way to tell males from females). Whether the interweaving of these organs results in chemical or just tactile signals is more than I can say, but every pair I watched engaged in it.
Once her eggs have been fertilized, a female seeks to lay them in a place where the larvae, when they hatch, can readily find larval bees, which the immature beetles eat to fuel their own development. In some cases, it’s known, larval blister beetles perch on flowers, wait for a bee to visit, and attach to the bee to obtain a free ride back to the bee’s nest. But the species of Meloe I was observing does it differently: I found two females positioning themselves at the mouth of the burrows of ground-nesting bees, which were plentiful in the area I was exploring, and carefully backing down into the bee burrow, presumably to lay eggs in underground chambers prepared and provisioned by the bee for her own offspring.
The fit is tight, given the bulbous abdomen of a female blister beetle, but each beetle backed in far enough to be completely out of sight, emerging after about five minutes underground. I’ve noticed many of the burrows of these ground-nesting bees occupied by adult bees, poised just inside the burrow’s entrance. Presumably this is guarding behavior, and also presumably, egg-laying blister beetles are high on the list of things the bees are guarding against.
It’s a quandary for the bee, I imagine. On the one hand, they surely want to spend lots of time gathering pollen so they can richly provision their larval chambers. But each trip abroad for pollen leaves the burrow vulnerable to parasitism by blister beetles. Likewise, being a larger than average bee probably helps with pollen gathering — but the larger-diameter burrows dug by larger bees must surely be easier for blister beetles to invade.
it’s a fascinating interrelationship. I still have a lot to learn about these impressive beetles. But with good luck and an hour’s observation, I learned more about them than I did in the past several years combined. There’s nothing like firsthand observation!