Major players in our ecosystem, bees and wasps are highly evolved, highly diverse, and endlessly interesting to watch.
Midsummer is peak season for most types of insects, but especially evident right now are the panoply of bees and wasps that live here. While it’s usually clear if an insect is a bee or a wasp, the distinction actually seems somewhat arbitrary to my inexpert eyes. Bees, in general, are plump and fuzzy; wasps are lanky and while they may have spines or hairs, they generally don’t look furry. In any case, one peculiarity marks this entire group of insects: while they have two wings on each side, the hind wing is much smaller than the front wing, and the two are locked together into a single unit, which looks and functions like a single wing, by a row of special anatomical hooks.
As a group, the bees and wasps are unfairly maligned. With the current concern over declines in pollinator populations, pretty much everyone understands that bees and wasps of beneficial because of their role in transporting pollen from plant to plant. But these insects are still stigmatized as aggressive and feared because they can sting.
To be sure, there are a few species of each that are irritable enough to make awkward neighbors. The so-called social bees and wasps, that is, the species that live in large colonies and build elaborate nests, certainly will sting in defense of their homes. (Wouldn’t you?) Honeybees, yellow-jackets, and paper wasps all fall into this class. But the vast majority of our bees and wasps nest alone or in small groups and invest relatively little effort in their nests (which may be underground or in dead vegetation). While capable of stinging, most of these species are docile, and some, quite literally, won’t sting even if you try to make them (yes, people have experimented!). And even the social bees and wasps are generally quite amiable when they are out foraging, away from their nests.
The self-defense capability of bees and wasps does give these insects a degree of immunity from attack. Accordingly, they’ve evolved striking color schemes, usually involving black and yellow stripes, as a warning to would-be predators. It doesn’t always work; many species of birds, for example, snag wasps with impunity, often rubbing the stingers off on a branch before swallowing them. But the cautionary markings are effective enough so that other insects have evolved patterns that mimic those of bees and wasps: some hover-flies and bee-flies, for instance, look enough like bees that it takes a careful look and a knowledgeable eye to spot the difference. (Handy short-cut: flies almost invariably have short, stubby antennae, while antennae on bees and wasps are longer and often sharply bent.)
Solitary bees and wasps share a fondness for visiting flowers, and they are equipped with long tongues with which they extract pollen or nectar from blossoms. A great way, therefore, to get acquainted with these insects is to keep an eye on the same flowers that butterflies like to visit: milkweed, goldenrod, or garden plants like blazing star, butterfly-bush, or lavender, for instance. In good habitat, it’s not uncommon to find five or six species of bees and wasps feeding on the same cluster of flowers.
The dietary preferences of bees and wasps diverge, though, when it comes to the provisions they make for their offspring. Bees typically stock their nests with pollen, which they gather industriously and transport to their nests in specially designed sacks on their legs. Pollen grains stuck to the insect’s body get transported to other flowers, and it is the very hairy bodies of bees that make them such effective pollinators. Solitary wasps, in contrast, transport pollen less effectively and generally lay in a supply of arthropod meat for their young.
The process is a bit grisly, though it works out well from the human perspective: solitary wasps are important players in controlling populations of insects that eat plants, including crops and ornamentals. Here is where solitary wasps put their stingers to use: finding a suitable prey item (and most wasps are quite specific about the kind of arthropods they prefer), the adult wasp stings its victim, paralyzing it, and then hauls it back to the nest it has prepared.
Wasp eggs are laid on or next to the immobilized prey, and upon hatching, the wasp larvae feeds on the victim. It’s a fascinating bit of biology. Species taken as prey range from spiders to cicadas to grasshoppers; there are even wasps that capture bees. Some wasps subdue and carry prey considerably larger than themselves: I’ve seen a wasp carrying a bush-katydid that must have weighed twice as much as its captor.
Major players in our ecosystem, bees and wasps are highly evolved, highly diverse, and endlessly interesting to watch (as long as you give wide berth to the nests of social species). Give them some of your attention this summer.