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.

Early Wednesday morning, the small, open nest of the Polistes wasps at the corner of the chlorination cage (near the top right corner of the cage in photo at left) was greeted by a creature wearing a black gas mask, along with a yellow rubber apron and garish green elbow length gloves that covered most of the monster's famous white shirt. These beautiful and gentle wasps have a sort of bovine curiosity, and cluster shoulder-to-shoulder to watch the changing of our chlorine cylinder. We use the chlorine dioxide gas to disinfect our irrigation water. Changing cylinders is a potentially dangerous task that must be conducted seriously with redundant checks, and early in the day when the body and mind are still fresh. The tank is placed on classic balance beam scale such as you find in an old doctor's office. When the tank's weight drops by 150 pounds it is empty. The Polistes were unaffected by the oddly clad visitor and the rattling of their residence, as the empty tank was removed, the heavy new tank wrestled upon the scale, and the new tare noted in the log book. All in a day's life for the Polistes.

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.

Farm Bulletin: Consider the Grass-Carrying Wasp

I was first captured by contributor Anthony Boutard's writing when I read his description of the barn owls on his farm: "Barn owl school started this week. You know the semester has started when you enter the barn and the ground is littered with dead mice and voles. We entered the barn early one overcast morning this week and disrupted class. The adults skedaddled into the box, leaving three of the immature birds fluttering around the barn in a state of panic. The fourth was calm and just watched us." I've been a fan ever since.

Ecce Isodontia

Against the dark foliage of the Douglas firs, long yellow wisps of dry grass float by against the wind. The scene could, at a glance, be one of Miyazaki's haunting animations. The creature animating each piece of grass is called the "Grass-carrying Wasp." These thread-waisted wasps belong to the genus Isodontia, a taxon distinguished by the grass-carrying habit. They are part of the larger Sphecid family which includes the mud daubers and digger wasps. The Sphecids are all solitary predators.

A grass-carrying wasp caught in the activity for which it was named.

The grass-carriers use existing cavities to build their nests, and those cavities may be part of your house. On our house, they nest in the space between the corner-boards and the shiplap siding. For the fields, we have built boxes with hundreds of bamboo segments to provide nesting habitat for cavity-nesting bees and wasps. We favor bamboo because each pole will have a range of cavity sizes, so we attract everything from the tiniest mason bee to relatively large wasps. They coexist happily. Bamboo is also more sanitary over time than the commonly used paper tubes, and it never gets soggy during the winter monsoons.  

The female Isodontia constructs the nest by lining the cavity with grass, and then provisions it with young grasshoppers, katydids and crickets. The wasp injects venom into the prey and cradles the insect between its legs, grasps  the antennae with its mandibles, then flies to the nest. She drags the insect into the hole, executes a U-turn, and comes out head first. A neat feat given the space constraints. Her wings are pretty ragged by the end of the season.

The poor prey must be thinking, "I have a bad feeling about this…"

She lays her eggs among the prey, then plugs the nest with more grass. The grass is carried the same way as the prey, one end in the mandibles and the other end cradled in the legs. As the grass blade is several times longer than the wasp, it streams behind her.

The eggs hatch and the larvae feed on the stored insects and then pupate over the winter, emerging next summer as adults. The last eggs laid grow into males and exit first, followed a week or so later by the females. Mason bees follow the same pattern. The males are smaller and built for the nuptial rites alone, while the larger female is left with all of the post-nuptial chores.

Hers is not easy work. As the wasp approaches the cavity, a yellow-jacket swoops down, hoping she will drop her prey. It hazes her whether she bears a cricket or a blade of grass, clearly unable to distinguish between her loads. At the nesting box, other smaller wasps scurry around. They may be "cuckoo types" that lay an egg on her prey in her absence, or parasitic wasps that feed upon the developing larvae themselves.

We seem to have at least two species nesting here. Some of the the nests are plugged neatly, looking just like the end of a factory-made cigarette. Other nests are plugged with the grass sticking out, Cheech Marin style. The wasps we see at the moment, with their reddish legs and wings, are probably the species Isodontia elegans. The adults are survive on nectar.

Like all other wasps, our grass carriers can inflict a painful sting. We live among a large number of wasps and bees on the farm, and the only one to sting us unprovoked is the domesticated honey bee. When nectar is short in late summer, honey bees become very aggressive. Over the course of the summer, we will be stung many times by the "gentle" honey bee. Other wasps and bees steer clear of us, and only attack when we actually disturb their nest.