May/June 2015For Wildlife Watchers: Red Paper Waspby Rob Simbeck
Wasps of all kinds have earned the respect of humans (as well as some degree of fear), and our awe hasn't diminished.
A wildlife biologist once told me about a hummingbird he saw go after a hawk. There was more than a touch of awe in his voice.
"That's a pretty impressive weight-to-weight ratio," he said.
It sure is. Given weights of less than half-an-ounce and three pounds, respectively, that ratio is at least 200-to-1, which, I'll grant you, is impressive. But consider a red wasp vs. an NFL lineman. That weight-to-weight ratio is more like 135,000-to-1, but I'm still betting on the wasp.
Wasps of all kinds have earned the respect of humans (as well as some degree of fear), and our awe hasn't diminished as we've learned more about them. The smallest wasps - less than a hundredth of an inch long - parasitize the eggs of other insects, including other parasitic wasps. There are more than 100,000 species of them, and, according to Lynn Kimsey, professor of entomology at the University of California at Davis, "We only have described, optimistically, half of them."
The largest is the tarantula hawk wasp, which is two inches long and, as the name implies, hunts tarantulas. Its sting is rated second worst in the insect world: "blinding, fierce, shockingly electric," says entomologist Justin O. Schmidt, creator of the Schmidt Sting Pain Index. Distinguishable by a pointed lower abdomen and narrow "waist" between abdomen and thorax, wasps are formidable killers. Parasitic wasps are often cited by those seeking to disabuse us of notions of peace and harmony in nature.
"I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of caterpillars," wrote Charles Darwin to his friend, the American naturalist Asa Gray.
But here in the Palmetto State, we are most familiar with the handful of hornets and stinging wasps that regularly cross our paths. As with most disquieting animals, our reaction is too often one of fear, leading to attempted extermination. However, like wasps throughout the world, these commonly-seen species are invaluable in keeping down the populations of crop-destroying and otherwise troublesome insects.
The red wasp, one of three hundred species of "paper" wasps (about twenty of which live in North America, depending on who's counting), is among the most familiar. In South Carolina, two species predominate - Polistes annularis and P. Carolina. To the untrained eye, the two are virtually indistinguishable from one another. We most often see their papery nests with distinctive hexagonal cells attached to porch ceilings, the underside of eaves and other spots in and around our homes and outbuildings. But they can also be found in trees and bushes - "almost any natural projection," says Eric Benson, a professor of entomology with Clemson's School of Agricultural, Forest and Environmental Sciences and a specialist with the University's Extension Service. Queens, each fertilized in the fall, will commonly get together in groups of up to twenty, with five as the average, to start a nest in early spring, usually in March or April in South Carolina.
"Eventually," says Benson, "one queen will dominate the others, making them serve as workers for the new colony," although, he adds, the competition may not be over completely. "The queen that wins the fight for dominance probably doesn't tolerate eggs from another subservient queen," he says, "but I wouldn't be surprised if a lesser queen doesn't try to slip her own eggs into the nest when she can."
Red Paper Wasp
Genus Polistes, "City Founder"
Description: One inch in length. Rusty red with black wings. Slender body, legs dangle as they fly.
Habitat and Range: Found throughout eastern U.S. including South Carolina. Found in trees, bushes and in and around buildings.
Reproduction: Nests founded by several females. Most eggs generally laid by one dominant queen.
Viewing Tips: Look for papery, umbrella-shaped nests.
A nest begins with a stem, called a pedicel, attached to a solid surface. Building under overhangs allows the wasps to stay out of both sun and rain. Added cells form a starter nest, with cells into which the queen lays eggs, fertilizing them with stored sperm as the others forage, build and defend the nest. Their strong jaws allow them to chew up wood from trees or boards, mix it with saliva and turn it into cellulose pulp.
Once these first eggs have hatched and reach the larval stage, they are fed by the workers, who kill and chew up caterpillars and sometimes adult flies, moths and other insects, carrying pieces back to the nest. This is where their usefulness to humans hits its peak, as they feed on any number of pests, including corn earworms, armyworms and hornworms. Each larva eventually spins a silk cocoon and encloses itself within the cell.
The first group to emerge is comprised of workers, sterile females who replace the original group of fertile females as foragers. Those other founders may be driven off by the queen, who then concentrates on laying eggs. Workers, like queens, are an inch long, slender bodied, with two pairs of deep purple to black wings and legs that dangle as they fly. They have large eyes, antennae (straight on females, curved on males) and a venomous sting courtesy of an adapted ovipositor. Anyone who's felt that sting has real incentive to avoid it thereafter. The nest continues to expand and may contain hundreds of cells by late summer.
"As the season progresses," says Benson, "males and the queens for the subsequent year are produced. Fertilized eggs become females and unfertilized eggs become male."
Females tend to mate close to the nest, while males will travel, helping to insure genetic diversity. The newly fertilized females will find sheltered places - behind bark, in a building - to overwinter, while the original queen, unmated workers and males die.
The overwintering queens emerge on warm days to consume nectar stored by workers in cells late in the season. When they emerge for good in the spring, they return to a spot near where they were raised and renew the cycle. They do not re-use nests.
Despite that fearsome sting, red wasps do have enemies. Ants are among them, although the pedicel contains liquids that repel them. Others include raccoons and some species of birds. Red wasps are themselves parasitized by another wasp (Elasmus polistis) and by the sooty-winged chalcoela, a moth that feeds on the larvae and pupae and lays its own eggs in the cells of red wasp nests.
A small percentage of people are allergic to the venom of these wasps, which can cause difficulty breathing or in some cases anaphylaxis, symptoms of which can include lightheadedness, cramps, nausea, a drop in blood pressure, diarrhea and shock. Still, if the nests are outside areas normally travelled by family members, they're worth leaving alone, since they help keep many garden pests in check. Every native creature has its role in a local environment, and if there's anything we should know as wildlife watchers, it's that it's worth getting past our kneejerk reactions to enjoy these and all the other fascinating creatures around us.