On The Trails: Wasps
- Mary F. Willson
- Mar 22
- 3 min read
By Mary F. Willson
The insect order Hymenoptera includes wasps and bees. Bees evolved from a waspish ancestor a long time ago and constitute a separate lineage, which is not the focus of this essay, although some comparisons are quite interesting.
Wasps are generally predatory, capturing caterpillars, spiders, beetles, and whatnot. They have powerful stingers, used to subdue prey and deter animals that threaten their nests. Their stingers are smooth and can be used multiple times, unlike those of honeybees. Along with the sting, they add venom of enzymes and proteins that cause serious tissue damage; multiple venomous stings from a group of disturbed wasps can create major medical problems in humans.
There are several kinds of wasps in Alaska. Paper wasps (Polistes) build comb nests consisting of numerous hexagonal cells that open downward (those of honeybees open upward); the cells are arrayed side by side, in a group that is suspended from house eaves or a branch. Female wasps chew up wood fibers to make the paper-like nesting material. The many cells are used to house developing larvae that are fed on chewed up arthropod prey.
The first eggs mature to become infertile worker females, helping maintain the nest. The next batch of eggs become males. And eggs of the final batch are fertilized and may become future queens with nests of their own. In our area, queens do not overwinter and nests only last a year, but farther south in warm regions queens and their nests may last more than one season.
Yellow jackets are chunkier than paper wasps. That name is used in two different ways: In a strict, narrow sense, it applies to the genus Vespula—the western yellow jacket, for example, which builds nests underground, perhaps in a rodent burrow, or in crevices in a wood pile. The comb is built of chewed up wood fibers. Larvae develop in the cells of the comb — they are fed on chewed up arthropods, carrion, and honey; they may secrete sugary nutritious liquids for the queen and young males. They mature in two or three weeks, then pupate before emerging as adults. The first ones are workers, helping the queen maintain the nest and foraging for other larvae; then both males and new queens are produced. An inseminated queen overwinters.
In the broad, informal sense, the name “yellow jacket” includes species that are sometimes called bald-faced hornets and classified in a different, closely related, genus (Dolichovespula). These hang their several combs inside a big ball of paper made from wood fibers chewed up with saliva. The big paper ball is often suspended from a branch or other structure; we sometimes see them along the trails.
The widespread group of pincer wasps (Dryinidae) also occurs in Alaska. The female pincer wasp has an unusual spring-loaded mechanism on the front leg; the foreleg has a comb-like array that closes very rapidly with an elongated claw on the tarsus, grabbing fast-moving prey. These slender wasps are parasitoids, laying eggs on nymphs or adults of leafhoppers or other insects, temporarily paralyzing the host. The larva develops inside the host at first, but older larvae are housed in a sac that protrudes from the host. They then pupate before emerging as adults.
Both wasps and honeybees make combs — arrays of hexagonal cells that story honey or larvae. Honeybees are famous for their waxy honeycomb. The word "comb" is an odd one. Online dictionaries and my big Webster printed dictionary provide lots of information about combs that are used to dress hair or organize textile threads, and combs that decorate the heads of roosters, for example. Strangely, those sources barely mention the word in connection with hymenoptera. So I have not discovered how that word came to be used for bee- and wasp-made combs. Interesting!
• Mary F. Willson is a retired professor of ecology. "On The Trails" appears periodically in the Juneau Independent. For a complete archive of Mary Willson’s “On the Trails” essays, go to https://onthetrailsjuneau.wordpress.com.
