Summer World_ A Season of Bounty - Bernd Heinrich [31]
6
Mud Daubers and Behavior
I’M NOT A GLUTTON FOR PUNISHMENT. IN ORDER TO get a kick out of nature—to enjoy insects, even stinging wasps—it is probably not necessary to risk life, limb, and anaphylactic shock. Indeed, I think I enhanced my educational experience, and possibly even advanced the cause of science, at least as much as I did by fooling around with the bald-faced hornets, during the summer of 2006, by sitting on our front porch sipping a glass of red wine with Rachel, my wife. It was early on a balmy August evening when big green darning needles, or dragonflies, were zigzagging back and forth in the clearing between our house and the bog. I was probably half dreaming about experiments I had done years earlier with a colleague, Timothy Casey, in which we had pinned them down and simulated overheating of their flight muscles (that they could normally experience in flight) by focusing a heat lamp on the thorax, and proved that they could stabilize their body temperature by shunting excess heat into their long cylindrical abdomen, which then served as a radiator. I had loved the control, the certainty, and the presumed cleverness of discovering a new phenomenon. Now, reminiscing, I still felt the glow, but in more ways than one, as I lifted the glass, looked out, saw the dragonflies, and then on the porch noticed a wasp dragging a spider.
The handsome blue wasp with dark wings carried the spider up onto a planter and tried to fly off with it, but the weight of the spider apparently pulled the wasp down: the wasp went only a short way before having to climb up a railing to make another short flight. I was wondering if the wasp’s flight muscles were not hot enough to generate sufficient lift to fly, or if the spider was too heavy for the wasp to carry. I didn’t know right away what kind of a wasp it was, except that it was a solitary wasp, unlike the hornets in yet another communal nest under our porch that I had recently offered, along with their nest, to my ravens.
As I was contemplating the wasp carrying the spider, Rachel casually mentioned having seen a wasp of the same description that had also been hovering along the side of the house, but she said that this one was carrying “a long piece of dry grass” and, furthermore, that she saw the wasp drag this grass into “a crack in the wall.” I know that wasps do some amazing things. But they always do the same things—they don’t vary their behavior. In short, I flat-out didn’t believe Rachel. But maybe I should have. I will get to the reason why shortly.
A few days later, under similar circumstances, I again saw the dark blue wasp—a female (male wasps don’t carry any objects)—carrying another spider. This time I followed her and saw her take the spider to a mud nest shaped like a long vertical tube that was plastered onto the south-facing wall of our house. Nearby, there were three of these nests of different lengths, neatly aligned adjacent to one another like the pipes of an organ. I knew from this nest that it was the organ-pipe mud dauber (Trypoxylon politum).
Insects are models that have given us a view into basic mechanisms of behavior and evolution. And birds, because they are emotional animals, provide a bridge to understanding ourselves. Their specialized behaviors—courting, vocalizing, nest building, foraging, habitat preferences, and strategies of parenting—are all deep-rooted in patterns that they are born with, as are those of insects. Insects show us how much can be done with a pinpoint-size brain, and they therefore seem magical. If so much can be programmed into such a small