Western yellowjacket, Vespula pensylvanica
Eastern yellowjacket, Vespula maculifrons
Southern yellowjacket, Vespula squamosa
German yellowjackets, Vespula germanica
Yellowjacket wasps are about 1/2 inch long with distinct yellow and black markings. Compared to honey bees, yellowjackets are sparsely haired. Wings are folded lengthwise, similar to paper wasps and hornets. They make an enclosed paper nest, usually located underground.
Occasionally nests will be constructed in walls or other protected sites. Portions of the paper nest may be visible where it extends beyond its protective shelter. Unlike “aerial yellowjacket” or hornet nests, exposed yellowjacket nests are not usually symmetrical in shape.
Yellowjacket wasps are social insects, living in colonies of hundreds to thousands. Like other social wasps, yellowjackets vigorously defend their nest against threats, such as people who get too close to the nest entrance. Guard wasps stationed near nest entrances use chemical communication to warn the colony of intruders. Hundreds or thousands of wasps can quickly emerge from a nest and attack people or animals that venture too close.
Yellowjackets are either scavengers or predators on other insects. Some species commonly scavenge for sweets and protein-rich foods in and around garbage cans and picnic areas, especially in the fall. In most parts of the country yellowjacket colonies die out each winter shortly after the first frost. Queen yellowjackets survive the winter in sheltered locations like buildings or outdoors under bark, stones, loose leaves or other shelter.
The objective of a yellowjacket management program should be to reduce human encounters with the wasps, but not to eliminate them from the entire area since they are beneficial predators of insects. The two most productive and least environmentally destructive ways to do this are to modify the habitat to reduce access to food in the vicinity of human activities, and to use physical controls such as trapping and nest removal.
A few tips on how to prevent or at least minimize being stung.
Yellowjacket nests can be located in a variety of places including in the ground, in masonry or other wall voids, on the eaves of buildings, on fences or in trees. Ground nests are often in sheltered locations such as under shrubs. In environments where these species occur frequently, a monthly inspection of buildings and grounds for nests during the active season may be warranted, with more frequent inspections during nesting seasons for problem species.
One teacher/staff complaint(s) received, or 5 or more wasps observed near food or picnic tables.
If non-chemical methods alone prove insufficient to solve the problem, then integrating a pesticide into your management program may be warranted. Always read and follow the label. The label is the law. Pesticides must be used in accordance with federal, state and local regulations. Applicators must have proper credentialing to apply pesticides and should always wear personal protective equipment (PPE) as required by the pesticide label during applications. All labels and Material Safety Data Sheets (MSDS) for the pesticide products authorized for use in the IPM program should be maintained on file. When an insecticide is considered necessary for the control of yellowjackets, the best approach is to confine it to the nest itself. Anyone applying insecticides should use special clothing that protects against the chemical as well as against wasp stings. Insecticides should be applied in the evening or very early morning when children are absent, the wasps are inside the nest, and cooler temperatures reduce insect activity. A number of insecticides are registered for use against yellowjackets, the following are most appropriate for use in schools:
Residual dusts can be very effective at controlling nests found in wall voids and underground nests. The extent of wall void nest should be determined by listening for activity behind the wall surface. Once the boundaries of the nest have been determined, holes can be drilled into the wall and an appropriately labeled residual dust can applied. The subsequent holes can be plugged with steel wool to prevent the wasps' escape. Outdoor ground nests can be similarly controlled by approaching the nest at night and dusting the entrance; this procedure should be followed by plugging the entrance with dusted steel wool.
Silica aerogel combined with pyrethrins is an effective insecticidal dust that can be used to destroy an underground nest or a nest in a wall void. Silica aerogel is made from sand and works by absorbing the outer waxy coating on insect bodies. Once this coating is gone, the insects cannot retain water and die of dehydration.
Pyrethrins can be used to quickly knock down guard wasps at the nest entrance and to kill yellowjackets in aerial nests when they must be destroyed in the daytime. These aerosol products are designed to project a stream of spray 10 to 20 feet and contain highly evaporative substances that "freeze" or stun the yellowjackets.
Gasoline should never be poured into underground nest holes. This dangerous practice creates a fire hazard, contaminates the soil, and prevents the growth of vegetation for some time. A ground application of gasoline poses greater harm to children and the environment than a yellowjacket nest.
Some “green” products may be found as part of EPA’s 25(b) exempt list. EPA describes the criteria for 25(b) products as: “Minimum risk pesticides that meet certain criteria are exempt from federal registration under section 25(b) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The U.S. Environmental Protection Agency (EPA) does not review or register pesticides that satisfy the 25(b) criteria, though registration is required by most states. For information on minimum risk pesticides in your state, please contact your state's pesticide registration office.” (http://www.epa.gov/opp00001/biopesticides/regtools/25b_list.htm)
The EPA also cautions that: “Products intended for the control of public health pests must be effective. EPA received a petition from the Consumer Specialty Products Association (CSPA) dated March 15, 2006, requesting that the Agency exclude from the minimum risk pesticide exemption those pesticides that claim to control “pests of significant public health importance” and require an abbreviated registration for minimum risk products that are to be used for the control of public health pests. On September 13, 2006, EPA published in the Federal Register a Notice of Availability and Request for Comments on the petition allowing a 60-day comment period. On December 6, 2006, EPA reopened the comment period for an additional 30 days at the request of CropLife America. During the public comment period, the Agency received approximately 60 comments, both in support of and in opposition to the petition.”
Hang traps to attract yellowjackets in the early spring to attract overwintering females and decrease the potential population. Trapping also works to kill foraging wasps and draws foragers away from areas of high human activity.
Traps designed especially for yellowjacket wasps are available from a variety of sources.
There are currently no effective, low-impact insecticides for quickly eliminating underground yellowjacket colonies. Pyrethroid insecticides work well and should pose no significant environmental or health risks when applied directly to yellowjacket nests.
Wasps, including yellowjackets, paper wasps and hornets can sting multiple times while honey bees can only sting once. (Other types of bees usually do not sting, but when they do, should be treated like wasp stings.) Honey bees leave the stinger in the skin via a handy barb. Here is where the treatment difference comes in. Immediately after the sting, the stinger needs to be removed. Attached to the stinger is a poison sac that continues to pump venom into the sting site for several minutes. This stinger should not be pulled out; rather, it should be scraped off. A stiff sheet of paper or a credit card works well for this. A wasp sting does not require scraping.
First, move to a safe location to avoid being stung repeatedly. After you have identified the offending organism and, if needed, removed the stinger, be sure to observe the patient for any signs of allergic reaction. If the patient has a history of allergic reactions, shows signs of severe swelling or has trouble breathing, a physician should be contacted immediately. If the patient shows no signs of distress, the sting area can be soothed by applying an cold pack to reduce swelling. An over-the-counter insect bite and sting product may be applied. Home remedies include applying a paste of baking soda or meat tenderizer and water. An antihistamine may also be given to relieve the itching caused by the sting.
Authors: Compiled from publications by Mike Merchant (Texas AgriLife), Dale Pollet (LSU), Daar, S., T. Drlik, H. Olkowski and W. Olkowski. 1997. Integrated Pest Management for Schools: A How-To Manual. Publication no. EPA 909-B-97-001. US EPA, Washington, D.C. www.epa.gov/pesticides/ipm/schoolipm/index.html