YELLOWJACKETS
THE COMMON YELLOWJACKET (Vespula vulgaris)
V. vulgaris ranges across Canada and the northeastern United States. Common in higher elevations, it nests in shady evergreen forests around parks and camps in the western mountains and the eastern Appalachians. This species also is one of the most important stinging insects in Europe.
They begin their nests with an enveloped small comb made of wood fiber paper, started in soil depressions, rodent burrows, or in any small hole in the ground that will give protection until workers can develop. Yellowjacket (with eighteen species in North America) colonies begin with a large fertilized queen; she develops smaller daughter workers and later reproductives just as the Paper wasps, but the nest structure is not the same. Some yellowjacket nests hang in trees and shrubs, and some are developed underground.
Once workers begin nest care, they enlarge the entrance hole and expand the nest. Combs are placed in tiers, one below the other. They can be very large; they have firm support from the soil surrounding the external envelope. Several species of Vespula make their nests in building wall voids, attics, hollow trees and other enclosed spaces as well as the ground.
Of the species in North America, only a few require pest management. These few species have certain characteristics and habits that put them on a collision course with people:
- They can live in what might be called disturbed environments (areas that have been changed to suit human activities in urban settings) such as yards, golf courses, parks, and other recreation areas.
- They have large colonies -- some will develop thousands of workers.
- Their habits do not restrict them to a specific kind of prey. Foraging workers capture insects for their larvae and nectar and other sweet carbohydrates for themselves where they can find it. Essentially, they are scavengers and work over garbage cans and dumpsters. They especially enjoy picnics and football games!
One can easily see that these habits put a large number of foraging stinging insects into close association with large populations of humans!
A Few Important Species
THE EASTERN YELLOWJACKET (Vespula maculifrons)
This common ground nesting yellowjacket is distributed over the eastern half of the United States. Its western border is from eastern Texas north to eastern North Dakota. Workers are slightly smaller than most yellowjackets, but colony size can number around 5,000 or more individuals. The nest of V. maculifrons is dark tan, made of partially decomposed wood and is quite brittle. The Eastern yellowjacket sometimes nests in building wall voids.
Most yellowjackets have very slightly barbed stingers but the sting will not set in the victim's tissue like the barbed stinger of the honey bee. The stinger of V. maculifrons, however, often sticks and when the insect is slapped off, the stinger may remain.
THE GERMAN YELLOWJACKET (Vespula germanica)
In Europe, German yellowjacket nests are subterranean, but in North America the vast majority of reported nests are in structures. This yellowjacket is distributed throughout the northeastern quarter of the United States. Nests in attics and wall voids are large, and workers can chew through ceilings and walls into adjacent rooms. The nest and nest envelope of this yellowjacket is made of strong light gray paper. Colonies of this yellowjacket may be active in protected voids into November and December when outside temperatures are not severe.
The Aerial Yellowjacket and the Bald Faced Hornet
Several yellowjackets make the aerial football - shaped paper nests, commonly called hornets' nests. Two of these yellowjackets are common: the Aerial yellowjacket, Dolichovespula arenaria, and the Bald Faced hornet, Dolichovespula maculata.
The aerial yellowjacket is found in the west, Canada, and east, although not in the central and southern states. This species begins its nest in March or April and is finished and no longer active by the end of July. Their nests, usually attached to building overhangs are smaller and more round than those of other species.
The Bald Faced hornet is larger than the other yellowjackets and is black and white - not black and yellow. It lives along the west coast, across Canada, and in all of the states in the eastern half of the country.
On warm spring days, the large Aerial nesting queen develops a small comb, like the Paper wasp with a dozen or so cells, but she encloses it in a round gray paper envelope. The daughter workers later take over the nest duties, and by mid summer, when the worker population is growing and food is plentiful, the nest is expanded to full size.
A full-sized Bald Faced hornet nest consists not of a single umbrella comb like the Paper wasp, but four to six wide circular combs -- one hanging below the other and all enclosed with an oval paper envelope consisting of several insulating layers. Bald faced hornets not only gather flies, but are large enough to kill and use other species of yellowjackets for larval food. They attach their nests to low shrubs or high in trees or on buildings. Although Aerial colonies can have four to seven hundred workers at one time, their food gathering habits do not routinely bring them in contact with humans. Large nests are often discovered only after leaves have fallen and the nests are exposed -- both to view and to nature's elements that finally bring about their disintegration.
MANAGEMENT OF YELLOWJACKETS
Problems with yellowjackets occur mainly when:
- Humans step on or jar a colony entrance.
- A colony has infested a wall void or attic and has either chewed through the wall into the house or the entrance hole is located in a place that threatens occupants as they enter or leave the building.
- Worker yellowjackets are no longer driven to feed larvae in the late summer months, and they wander, searching for nectar and juices -- finding ripe, fallen back yard fruit, beer, soft drinks and sweets at picnics, weddings, recreation areas, sporting events and other human gatherings.
Yellowjackets are sometimes responsible for injections of anerobic bacteria (organisms that cause blood poisoning). When yellowjackets frequent wet manure and sewage they pick up the bacteria on their abdomens and stingers. In essence, the stinger becomes a hypodermic needle. A contaminated stinger can inject the bacteria beneath the victim's skin. Blood poisoning should be kept in mind when yellowjacket stings are encountered.
Inspection
Sting victims often can identify the location of yellowjacket nests. Where the nest has not been located look in shrubbery, hedges, and low tree limbs for the Bald Faced hornet. Soil nests are often located under shrubs, logs, piles of rocks and other protected sites. Entrance holes sometimes have bare earth around them. Entrance holes in structures are usually marked by fast flying workers entering and leaving. Nests high in trees should not be problems. Be sure to wear a bee suit or tape trouser cuffs tight to shoes.
Habitat Alteration
- Management of outdoor food is very important.
- Clean garbage cans regularly and fit them with tight lids.
- Empty cans and dumpsters daily prior to periods of heavy human traffic at zoos, amusement parks, fairs and sporting events.
- Remove attractive refuse, such as bakery sweets, soft drink cans, and candy wrappers, several times a day during periods of wasp and yellowjacket activity.
- Locate food facilities strategically at late summer activities so that yellowjackets are not lured to dense crowds and events. [The National Park Service in their IPM programs, found that stings were dramatically reduced when drinks are served in cups with lids.]
- Clean drink dispensing machines; screen food dispensing stations, and locate trash cans away from food dispensing windows.
- To limit yellowjacket infestations in wall voids and attics, keep holes and entry spaces in siding caulked; screen ventilation openings.
For more information, please select these pages:
About the Bee
The Africanized Honey Bee (the "Killer Bee")
Carpenter Bees
Cicada Killer Wasps
Mud Dauber Wasps
The Giant Hornet Wasp
Paper Wasps
Get the Point about Bee Stings
