Ground Wasps

General Information

Ground wasps prevalent in the New England states include the cicada killer, Sphecius speciosus, and the great black wasp, Sphex pensylvanicus. Both insects utilize similar nesting characteristics and are solitary species, meaning the queen tends to build nests without the support of an established colony. The wasps are characterized by nesting habits that utilize ground-based dwellings.

Appearance & Identification

What does a ground wasp look like?
The cicada killer may grow up to two inches in length and is distinguishable by its rust-colored wings and thorax. The abdomen has black and yellow markings. Larger than many other species of wasps, the cicada killer may appear more threatening than it is. While both males and females possess stingers, males are incapable of stinging. At nearly one and a half inches in length, the great black wasp lives up to its sizable name. Adorned with heavy-duty mandibles that allow for firmly holding onto prey, the wasp also has the typical narrow “waist” found in most wasp species. Somewhat shiny black in coloration, the great black wasp has bristly legs and black wings that fold flat over the abdomen.

Habits/Habitat

Cicada killers dig tunnels in open areas such as lawns and pastures, while areas with workable soils are favored. Tunnel entrances are noticeable due to a mound of excavated dirt that surrounds the opening. Once fully developed, new female cicada killers may live up to a month but still produce tunnels reaching up to four feet in length, all in a single nest. A nest containing nine or 10 cells does not prove unusual. The great black wasp builds nests underground using methods similar to the cicada killer. Both types of wasps tend to be more active during the day, foraging and feeding, while returning to the nest at night to rest.

Diet

What does a ground wasp eat?
Cicada killers and great black wasps kill their prey with paralyzing stings then carry the food source back to the incubating larvae. Once hatched, cicada killer larvae will consume the entire food source, typically a cicada, hence the name. Within a month, the larvae finish growing, form a protective cocoon, and lie dormant. In spring, they pupate for about a month and then emerge as adults. The great black wasp attaches eggs to the underside of the prey insect. After hatching, the larval process lasts about 10 days before full-size wasps emerge. Adult wasps feed on other insects for protein early in the nesting season but mostly gain sustenance from fruits and sugars as the season draws to a close.

Reproduction

The cicada killer is a solitary insect. Queens mate then dig the tunnels themselves. After laying eggs in every cell, the wasp fills each cell with a captured and paralyzed cicada for the larva to eat. Once the nest is made and propagated, the queen leaves, never to return. Great black wasps are also singular insects. The fertilized queen digs tunnels similar to the cicada killer and fills each cell with captured grasshoppers or other similar insects. Great black wasps provide larvae with two or more grasshoppers in each cell to feed upon once hatched.

Problems Caused by Ground Wasps

Like any stinging insect, ground wasps like the great black wasp and cicada killer come into contact with humans from time to time. Both species tend to show aggression while hunting and if the nest is disturbed. Since both the great black wasp and cicada killer nest in the ground in soils, the possibility of damage does occur. If soils in gardens or around patios are loosened by the wasp, plants may not take root and the chance for damage to patios may occur. Ground nests near homes allow for more chances of interaction and possible stinging.

Signs of Infestation

The most obvious sign of ground wasp infestation relates to the small mounds of excavated dirt above the tunnel entrance. Slight damage to rooting plants in people’s gardens, as well as noticeable damage to lawns and sand-resting synthetic structures, may occur. Great black wasps serve as excellent control insects for grasshoppers and other katydids, while cicada killers also control cicada populations.

Prevention

Regularly inspect homes or businesses, especially around gardens, lawns, and man-made ground structures. In extreme cases, contacting a local pest control specialist may prove necessary. However, as both species of ground wasps control true pest populations, utilizing professional exterminators or over-the-counter pesticides should probably only be considered in severe circumstances. Consistent watering of garden soils may help move nests, as most ground wasps do not like wet soil. Consistently churning soils to discourage wasps from nesting in these areas may also prove an acceptable prevention technique.