School Integrated Pest Management (IPM) for Wasps and Bees

Publication Number 444-510, Posted June 2003

Important Note

Introduction

Biology and Identification

All bee species and most wasp species are winged. Bees can be distinguished from wasps by their stout, hairy bodies. Wasps, on the other hand, have relatively smooth, slender bodies. Another important difference between bees and wasps is their stinger. Bees have barbed stingers. Therefore, a bee can only sting once, leaving the stinger within the victim. Wasp stingers lack the barb so wasps can sting multiple times in defense of their nest.

Bees and wasps experience complete metamorphosis. This means that they pass through four different life stages: egg, larva, pupa, and adult. (See Figure 1.) Newly hatched individuals are called larvae. Larvae are blind and legless. After the larval stage, they become pupae. The pupal stage is a non-feeding, immobile stage wherein the larvae transform into adults. Finally, the bees and wasps emerge from the pupal stage as fully developed adults.

Wasps and bees display various levels of social behavior ranging from non-social, solitary mud daubers to highly social honeybees. The social species of wasps and bees live together in highly organized communities where they share food resources and cooperate in raising the young. Most pestiferous wasps live in these types of large, organized colonies. Ground-nesting wasps, such as yellow jackets, often build subterranean paper nests. Other species of wasps build aerial paper nests in trees, under eaves, or within wall voids. (See Figure 2.) These nests can contain thousands of individuals, all with the ability to sting. Some solitary species, such as mud daubers, construct galleries of mud where they stash paralyzed spiders and other prey. After laying an egg in the gallery, the female seals it shut, thus leaving a plentiful food supply for the next generation. Solitary wasps will sting if provoked.

Bees and wasps become increasingly abundant and active from spring through fall as the temperature rises and food sources become more available. Bees feed on nectar and pollen from flowering plants. Wasps feed primarily on protein sources, such as spiders and insects, but they will also readily feed on sugar sources. Wasps, because of their food preferences, often scavenge around humans. Human activities provide a ready supply of protein and sugar.

Foraging bees and wasps will normally refrain from stinging unless threatened. Yet, if the colony is threatened these insects will vigorously defend their nest. Disturbing a colony can occur when someone accidentally steps on or mows over an underground nest opening, agitates a tree or bush containing an aerial nest, or even walks past a previously agitated nest.

If bees or wasps or their nests have become a nuisance, remember that control can be a hazardous undertaking and should only be done after considering all safety precautions. If nests are large, it may be advisable to have professional pest control operators handle the situation.

Prevention

1. Keep all outside trash receptacles tightly covered.
2. Remove trash from within all receptacles frequently. This will assure that trash will not prevent the lid from closing securely over the receptacle.
3. Clean dumpsters frequently.
4. Remove any dependable water source near the structure. Repair leaky outdoor faucets. Direct air conditioner drainage to areas where water will not pool. If you have depressed areas where water pools after a rain, level the areas to prevent future pooling.
5. Caulk any holes and cracks in the building that can be used by bees or wasps to gain access into the structure. Bees and wasps may use these as entryways to establish nesting sites within the structure.
6. Make sure storm windows and screens are tight fitting and in good condition.

Monitoring and Inspection

Nests can be found underground, under eaves, in wall voids, and in trees and shrubs. Inspect bushes, logs, rock piles, and other protected sites for the presence of nests. In order to determine the continued success of your management plan and to locate new nests, continue monitoring on a regular basis throughout your integrated pest management (IPM) program.

Regularly inspect the premises during the spring and early summer. Inspecting during the spring and early summer will allow you to detect incipient nests. Incipient nests are easier to remove than mature nests.

Least Toxic Control Methods

Before performing any type of control measure, understand that nighttime removal reduces the risk of being stung since the insects are slower and may have a more difficult time finding the source of the disturbance. In addition, at night wasps and bees are not foraging but are in their nests. Finally, at night children are not present on school grounds, reducing the risk that a stinging event will occur.

Physical Removal

1. Trapping for wasps (particularly yellow jackets) can be an effective tool for reducing foraging wasps in an area. Several traps on the market utilize bait to attract wasps. Other traps, such as sticky traps, use colors (especially yellow) to attract the wasps. Trapped wasps die when placed in a freezer for a few hours.
2. Nest removal is also possible if you take the proper precautions. If the nest is in an accessible area (like hanging from a tree branch), you can use a strong plastic bag to enclose the nest. You can then sever the base of the nest or branch and remove the nest.
3. Vacuuming out entire nests is another option. We recommend that only a professional do this since special equipment is needed. Vacuuming can be particularly useful when bees or wasps are found within a wall void or in an environmentally sensitive area where pesticides cannot be used. If you use a vacuum, remember that once the vacuum is turned off, the wasps will be able to find their way out of the vacuum. Therefore, it is important to quickly seal the vacuum bag and remove it from the vacuum cleaner. Placing the bag into a freezer for a few hours will kill the wasps.

Chemical Management

Whatever the control method you choose, it is imperative that you keep clear, accurate records of all actions taken.

Different chemically based management suggestions are listed below.

1. Aerosol sprays can be used to quickly knock down and kill individual nuisance bees and wasps. Only a small amount of spray is needed to kill the individual. Aerosols can also be used once a nest has been removed and placed into a bag. A small amount of the insecticide can be sprayed into the bag, providing the necessary lethal dosage.
2. Silica aerogel dust can be applied along with aerosol sprays to destroy underground nests. The pyrethroid acts as a quick knockdown agent and the silica aerogel acts as a long-term insecticide. The silica aerogel works by absorbing the outer waxy layer on insect bodies. Without the waxy layer, insects dehydrate relatively quickly.
3. Do NOT use gasoline in any situation. Gasoline is highly flammable and volatile. In addition, gasoline renders the treated soil infertile. Soil often absorbs the gasoline before it contacts the nest. The resulting fumes, instead of having the desired effect, actually irritate the wasps and may make the problem worse. Using gasoline is a very dangerous procedure.

Record Keeping

INTEGRATED PEST MANAGEMENT (IPM) TECHNIQUES
The Four-Step Plan

• Prevention
• Monitoring and Inspection
• Least Toxic
  Control Methods
• Record Keeping

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