Saturday, September 03, 2011
Farm Bulletin: Polite Society
There are many reasons I love publishing the essays of contributor Anthony Boutard—his slow, even, considered style and his dry wit among them. But chiefly it's because of the passion he so ably communicates about his work at Ayers Creek Farm. We city folks rarely consider the insects and smaller creatures around us unless they crawl or burrow into our lives, and then the usual response is a lethal one. Anthony gives us a reason to reconsider our reaction.
The Polistes can deliver a painful sting, but they are by nature laconic souls, so much so that we call them the "polite wasps." In twelve years of working around these wasps, I have been stung once when I moved the pump to its summer position. We don't like to kill them, so where they are unwelcome, such as inside the pump housing, we spray the area with Fluid Film, a non-toxic, lanolin-based lubricant of choice on the farm. They cannot build a nest on the greasy surface. Polistes feed their larvae chewed up caterpillars, earning them accolades as beneficial insects, part of the web of relationships necessary for a successful organic farm. Those that nest on our heavy truck enjoy day trips to Canby, Needy and Cornelius without any noticeable attrition in their numbers. We have two nests in the cowling of our blast sprayer, and they tolerate the howling fan and heady brew we use as a foliar feed. Almost every one of the large steel pipes at end of our berry trellises has a nest inside.
Polistes are social wasps. After mating in the autumn, the females overwinter clustered in a tree cavity or more commonly in birdhouses at Ayers Creek. They are called foundresses, and come the following summer they establish the new nests. Either a single foundress or a group of sister foundresses will create a new colony. In the case of those with multiple foundresses, one will be the dominant queen and the others subordinates, or workers. Unlike the other social Hymenoptera (ants, bees and wasps) where the female workers are sterile, in Polistes the subordinates can and do lay eggs when the queen isn't paying attention (the nest with eggs and larvae at right). Recent research published last month in Science (v. 333:874), also revealed that completely unrelated females often live in the colony and sneak an occasional egg into the mix. Apparently larger colonies confer certain advantages that outweigh the loss of strict breeding controls that exist in a smaller, single foundress colony.
We often regard social behavior in the social insects as a very mechanical, fixed structure, but in the case of Polistes, different arrangements are possible even in their polite society. Interestingly, salmon exhibit a similar phenomenon, where a small percentage are born pioneers and forsake the natal stream for a new and unfamiliar one. The acorn woodpeckers that nest as a colony in oaks exhibit a similar structure to Polistes. Unrelated acorn woodpeckers can be members of the colony and participate in managing the acorn granaries and raising the young. And in some species of songbirds, the male will help raise the clutch even though not all of the chicks share his genes. Complex and varying family structures are probably the norm in nature, despite what the nagging moralists would have us believe.
When you grab a can of spray to send these gentle Polistes to their death, ponder for a moment the work they do about the yard picking caterpillars off your cabbages and roses. If that fails to sway you, glance into the eyes of the pale larvae in each of the outer paper cells and consider that one of them might be the offspring of a plucky outsider who managed to sneak in an egg against the social conventions of the colony. Yes, September should be "Appreciate the Hymenoptera Month" as it is certainly the time when this great and varied insect order reaches its peak population. Have a heart and give a pass to Polistes.