Wasps are members of the order Hymenoptera (skin wings) and come in many types and sizes. The ones that are of most concern to people because of their stinging habits belong to the families Vespidae and Sphecidae. The family Vespidae has seven subfamilies in North America, containing many common wasp species, like yellowjackets and hornets. Their social organizations range from cooperative fertile female paper wasps to the caste system of yellowjackets, in which there is a single fertile queen and a large population of smaller unmated females. Due to their size and coloration these wasps are often mistaken for bees. Bees are not nearly as aggressive and are valued as major pollinators as well as honey producers.
Yellowjackets (Vespula spp.)
Description: 12-17.5 mm in length; head, thorax, and abdomen black and yellow or white; body fairly stout; wings smoky.
Range: Throughout North America.
Food: Adults feed on nectar and other insects, larvae are provided with pre-chewed insects and pieces of meat. Adults can become pests around outdoor eating areas and garbage cans because they are always scavenging for food scrapes. They also forage for sources of sugars or other carbohydrates, such as beer, fruit, and sweet beverages. As the new queens are produced in the colony in late summer, they demand sugars from the workers, which the forage aggressively for sources of sugar. They are very aggressive and will sting repeatedly at the least provocation.
Habitat: Meadows, gardens, hedges, around homes, and forest edges. They usually nest underground in an old rodent burrow, beneath a landscape timber, or in a rock wall or wall of a building, or at ground level in fallen logs and tree stumps. In urban settings they can also be found under stairs, in fence posts, brick walls and discarded mattresses, carpets, boxes, etc. The German yellowjackets are often found nesting in wall voids, attics, or crawl spaces. Whether in the ground or within a wall void, the yellowjackets nests are made of wood pulp and saliva used to form layers of cells encased in a protective paper covering.
Life cycle: In the spring the fertilized female builds a small nest and begins laying eggs. She tends to the resulting larvae until the first brood matures into female workers, which rear consequent larvae and extend the nest. As many as several thousand workers may be produced in a colony in one season. Males develop from unfertilized eggs toward the end of summer and mate. At the onset of cold weather all the wasps, including the old queen, die except young mated females which over winter among leaf litter or in soil.
Bald-faced Hornets (Dolichovespula maculata)
Description: 16-20mm in length; body stout with black and ivory white markings on the face, thorax, abdomen, and first antennal segment; wings smoky. These are not true hornets but are members of the wasp family.
Range: Throughout North America
Food: Adults consume fruit, nectar and other insects; larvae are fed pre-chewed insects.
Habitat: Gardens, parkland, meadows, and forest edges. Nests are constructed out of wood pulp and saliva and attached to branches in the open. They consist of many layers of cells encased in protective paper with an opening at the bottom. The nest resembles a large inverted teardrop shaped ball, and can contain thousands of wasps, which are extremely aggressive when disturbed.
Life cycle: In the spring females construct small pendant nests with a few cells and begin laying eggs. The first brood matures into female workers, which feed the larvae several times a day and continue nest expansion. In the late summer males develop out of unfertilized eggs and mate. Only young mated females survive the winter in soil or among litter.
Paper Wasps (Polistes spp.)
Description: 13-25mm in length; body slender and mostly reddish brown to black with yellow rings and reddish areas on abdomen; wings reddish or amber brown.
Range: Throughout North America
Food: Adults feed on nectar and juices, larvae are fed pre-chewed insects. The Polistes wasps are very beneficial predators of caterpillars and they also have a sweet tooth later in the summer. They will seek out sweet secretions from fruit trees and other sources. Because of this they are probably more common in backyards that have fruit trees, picnic areas and heavy used camping sites.
Habitat: Fields, meadows, gardens, and near buildings. Nests are umbrella-shaped and consist of a single layer of cells constructed out of wood and saliva with openings at the bottom. The nests are located under eaves and ledges. The nests are rather small, rarely more than 6 to 8 inches in diameter, so there are seldom more than 100 to 200 workers on the nest at any one time. They often enter houses in the fall, seeking a place to hibernate. They rarely sting at this time unless handled. Paper wasps are not nearly as aggressive as yellow jackets or hornets.
Life cycle: In the spring several females construct a nest together. One of the females becomes the dominant queen and starts laying eggs. The first generation consists of females only, which are cared for as larvae by unmated females. In the late summer males emerge from unfertilized eggs and mate. Only newly mated females over winter under leaf litter and in stone walls.
The family Sphecidae is made up of a large variety of solitary hunting wasps. There are about 1200 species in North America, many of which are common. They feed upon spiders or insects such as aphids, caterpillars and cicadas. The hunting wasps feed this prey to their young, which develop in separate nests in the ground, natural openings or in cell constructed out of mud, like the mud daubers. The hunting wasps do not live in colonies but often may nest together in large numbers at a site. The solitary hunting wasps often are rather fearsome looking but rarely sting and do so only if handled. Most of these wasps are beneficial predators of pest species and do not require control.
Black-and-yellow Mud Dauber (Sceliphron caementarium)
Description: 25-30 mm in length; long cylindrical one segmented "waist" (pedicel) between thorax and abdomen; body black with large yellow area on prothorax; yellow pattern on thorax, pedicel, and 1st segment of abdomen; legs mostly yellow; wings brown-black.
Range: Throughout North America.
Food: Adults feed on nectar, larvae feed on provided spiders.
Habitat: Meadows, rock faces, settled areas, where nests are located under rocks, overhanging roofs and other structures.
Life cycle: Solitary female builds a nest out of moist mud containing several parallel cell rows. A paralyzed spider is stuffed into each cell and one egg deposited on each spider. The female then closes the cell opening with mud. Hatching larvae slowly consume the spiders after which they pupate inside the cell. Males are rarely seen before midsummer and feed on nectar.
Cicada killer (Sphecius speciosus)
Description: A large wasp, up to 2 inches long, with a black body and strikingly marked with yellow. Generally resembling a large hornet.
Food: The adult feeds on nectar. The larvae feed on spiders, caterpillars, cicadas, and other insects that have been stung and paralyzed by the adult female and placed in their cell.
Habitat: The female wasp excavates a large burrow about ½ inch in diameter, throwing the soil out of the burrow and leaving a small but unsightly mound of dirt at the entrance.
Life cycle: A single female wasp excavates their burrow and places food for the larvae into the burrow then lays an egg on the food and seals the cell. She then places more food in the burrow and lays another egg and seals that cell. These are not social insects, so each burrow is the result of efforts by a single female. But there may be several females in the same area. The only real damage done by cicada killer wasps is to lawns or flowerbeds. Females will not sting unless they are handled, but then their sting can be painful.
Unless wasps, hornets, and yellow jackets become a threat we urge you to leave them alone. They play an important role in the ecological balance of your backyard, neighborhood and local community.
Yellowjackets and hornets are outside the nest during the daylight hours. Nearly the entire colony is in the nest during the evening and nighttime hours, although some workers may be stranded away from the nest and will not return until morning. Control measures for hornets and yellowjackets should be attempted during the nighttime hours when the whole colony is in or on the nest. Paper wasps (Polistes spp.) can usually be treated during the daytime, because these wasps are not as aggressive in their nest protection behavior as hornets and yellowjackets.
There are many insecticides labeled for controlling wasps, when applied into or onto the nest. The difficulty involves making the treatment without being stung. If applications must be made during the day, protective equipment such as boots, heavy coveralls, veiled headwear, and heavy gloves should be worn. This equipment should be carefully secured in such a fashion that wasps can not slip under cuffs or other areas of the clothing. Use plenty of masking tape wrapped around the bottoms of pant legs and sleeves and around the collar.
For Polistes nests, an aerosol spray of one of the many fast-acting wasp killer aerosols will quickly kill all workers present on the nests. After the colony has been killed with the initial insecticide application, the nest should be scraped or knocked down and removed so as not to attract dermestid beetles at some later time, and to keep wasp pupae from possibly reestablishing the worker force. After the nests are removed, be sure that a spray or dust residue of a residual insecticide is left in the nest area to ensure that any worker wasps not present at the time of initial treatment will be killed later.
The most difficult problems in wasp control are generally those that involve large aerial nests of yellowjackets or bald-faced hornets and ground or structural nests of yellowjackets. Control of aerial nests of hornets and yellowjackets should be attempted only while wearing a full set of protective equipment. A liberal amount of material should usually be applied, up to one large can of aerosol wasp killer. Direct this spray into the hole at the bottom of the nest, being careful not to break open the side of the nest. Within a few hours, or certainly by the next day, all the colony members should be killed by this initial application. Before nest removal on the next day, a few seconds of aerosol spray should be directed into the nest entrance to be certain all wasps have been killed. The nest can then be removed, if possible.
Control of ground-nesting yellowjacket nests is best done at night for safety reasons. The nest entrance should be located during the daytime and marked in some way for easy and precise location in the evening. When the nest is approached at night, it is a good idea to have the available light (spotlight or flashlight) set and focused on the nest from a distance, off to the side. Do not hold it in your hand, because it may attract attacking workers. It is safest to wear protective clothing. Approach the nest slowly and carefully. The quickest and surest way to kill the colony is to have a hand duster, loaded with carbaryl or bendiocarb dust and puff several large puffs of dust directly into the hole. Then apply more dust onto the area around the entrance hole. This should totally kill the colony by the end of the next day. If you do not have a hand duster, an empty dish soap squeeze bottle can be used. Be sure the bottle is clean and dry before adding the dust. Only fill the bottle half full, then shake it up to mix air and dust just before puffing into the entrance. Dust will travel deeper into the void, in the ground or wall, than will an aerosol wasp killer.
Cicada killers can be efficiently controlled by treatment with liquid insecticidal lawn sprays. Treat the ground area where the wasps are burrowing. Also, each burrow can be individually dusted with a dust formulation to control the wasps.
Mud daubers are not aggressive about defending nests under construction. However, protective clothing should be worn. A residual insecticide liquid or dust application to the mud nests and the surfaces in the immediate area will provide effective control. Then, scrape away and remove the nests, if possible.
If you are allergic or hypersensitive to wasp or bee stings you should not attempt to control these insects and should call a professional pest control company. Or if you do not have the proper equipment call a professional pest control company.