Wasps (Yellow Jackets)

Wasps (yellow jackets) generate fear in people usually when they are seen hovering around a garden or an outdoor activity. This is particularly true of people who have previously experienced a sting or those who have developed a sensitivity to the sting. Outdoor gatherings are usually visited by yellow jackets because of their attraction to meats and sweet foods. Stings often occur when people or animals disturb wasps while they are hunting for food or protecting the nest. Yellow jackets may also attack people or animals when unprovoked.

Yellow jacket wasps live in nests. Problems usually occur when the wasp or its nest is disturbed. They have the ability to sting as a means of ensuring survival. A hollow stinger is located at the rear of the yellow jacket’s body. Upon penetrating the skin, a venom is injected through the stinger. These stings can be quite painful. They can also be very dangerous to people who have developed an allergy to the stings. Unlike the bee, a yellow jacket can sting more than once. Wasps can also damage fruit when they create holes by eating the flesh.

People often mistake bees for yellow jackets because of their colouring, however they are very different. Bees sting once and then die, but wasps can sting repeatedly. Yellow jackets have a shiny black and yellow body and measure 2 to 3/4 inch (12-18 mm) in length. These social insects live in large caste-divided colonies.

Because yellow jackets are beneficial (they consume insects such as flies and caterpillars), try to tolerate small populations of them.


The life cycle of the yellow jacket consists of the egg, larva, pupa and adult life stages. Just before winter, the queen wasp mates and finds a suitable place to overwinter (ex. decaying stumps). The queen is the only one of the colony to overwinter (the rest die). When spring arrives, the queen comes out of dormancy, begins feeding and searches for a nest site to begin her new colony. She may find a suitable aerial location in a veranda, eave, tree or woodpile. Sometimes nests can be found in the ground. Once a location is found, she begins construction of the nest. The nest is made from a paper-like material gathered from decaying wood and fibres mixed with saliva. Each nest can contain anywhere from 20-45 cells.

The queen lays her eggs in the cells and protects them until the larvae emerge. The larvae are fed until they pupate. Adults emerge from the pupal cases approximately three weeks later. Sterile female workers, the first adults to emerge, take over most of the duties of the queen. As a colony becomes larger, the sole responsibility of the queen is to reproduce. Thus, the colony can become very large by late summer. It is during this time that the overwintering queens are produced.



The best method of control is to avoid contact with yellow jackets or any other kind of stinging insects. Because they are attracted to sweet food and strong scents, avoid leaving food or drink uncovered when eating outside, and wearing scented products such as perfume and hair spray. Keep garbage in sealed containers until it can be properly discarded. Be careful not to step on a yellow jacket when walking barefoot on lawns or other grassy areas.

If a wasp lands on you, remain calm and wait for it to fly off or brush it off gently. Otherwise, you run the risk of threatening the wasp and experiencing a sting. Seek medical attention when the reaction to a sting includes swelling, itching, dizziness or shortness of breath.

Trapping is a direct control method. Various commercial traps are available at garden centers and department stores. Bait can be used with these traps to increase the effectiveness of them by attracting more wasps. Another trapping option is to place a yellow pan filled with soapy water and sugar in an area where wasps are a problem. The sugar will attract the wasp and the soap will break the surface tension of the water. When the wasps land on the water, they will fall in and drown.

The removal of a wasp nest may be necessary if it is located near human activity or near a residence. Although the homeowner can remove a nest, professional help is advised. Nest removal can be dangerous and extreme caution must be used because of the danger of attack by a large group of wasps. It is recommended that the nest be removed just before dark. It is also recommended that it be removed in the spring when the wasps are small and populations are low. Always wear protective clothing to avoid being stung and do not use a light directly on the nest as this will alarm the wasps and increase their activity. Wasps enter through one entrance and once this is blocked, the wasps will remain in the nest. Place a bag around the nest, blocking the entrance and then cut the nest off. Dispose of the nest contents.


If physical control measures are not effective, use a pesticide which will have a minimal impact on both you and the environment. Wear protective clothing when applying pesticides to a nest. Aerosols containing pyrethrin, rotenone and pyrenone are available. These are the least-toxic products available. Insecticides in the form of dusts or baits can be used to control yellow jackets. The best approach is to apply a pesticide to the nest which will paralyze or stun the wasp immediately.