Social wasps are common in urban and rural areas throughout North America, and are the most common stinging menace in many Canadian cities.
Outdoor gatherings are often visited by wasps because of their attraction to sweet foods, but also to protein food earlier in the season. Stings can happen when people or animals bother wasps that are hunting for food or when they approach a nest by accident, triggering a defensive reaction from wasps guarding the nest. But wasps may sometimes attack people or animals even when seemingly unprovoked.
Several thousand people are stung by these venomous insects each year. In some rare cases, severe allergic reactions to the venom have caused death. Get medical attention right away if your reaction to a sting includes unusual swelling, itching, dizziness, or shortness of breath.
Unlike bees, wasps can sting more than once. Wasps can also damage ripe fruit by creating holes when they eat the flesh.
Wasps can be beneficial in many ways. Workers catch insects, like flies and caterpillars, and carry them back to the nest to feed the developing larvae. They also act as pollinators when they visit flowers for nectar. And they are a source of food for small mammals, birds, and spiders.
Given their beneficial role in nature, try to tolerate small populations of wasps. Use preventive practices to stop them from becoming intolerable. Learn to tell the difference between harmful social wasps and the solitary ones that are mostly harmless and beneficial.
Before wasps become a problem, inspect your yard and home surroundings in early summer, looking for any wasp activity or paper nests taking shape. It is easier to discourage a single queen wasp from establishing too close to your home than handle a full-sized nest later in the season.
You can find different commercial traps at garden centers and department stores. Food bait can be used with these traps to increase their effectiveness. Try to use protein foods (like dog food) instead of sweet foods so that bees are not trapped.
Be aware that there may be more wasp activity around baited traps, so they should not be placed close to play areas or other places of human activity. These traps can be useful in the short term during outdoor events where wasps can be drawn away from food-serving areas.
If the location of the nest does not present a health hazard, it's best to leave the nest until November or December. Once it has been abandoned, you can remove the nest and dispose of it with little risk.
If the nest must be removed when the wasps are active, it should be done in the evening when wasps are least active. Nest removal can be dangerous and extreme caution must be used because of the risk of attack by a large group of wasps. Although a homeowner (with enough protection) can remove a nest, professional help is recommended.
Depending on the location and structure of the nest, removal can be as simple as enclosing the nest in a plastic bag and detaching the single anchoring stalk from the supporting tree branch or structure. To dispose of the active nest, place in a freezer for at least 48 hours. Remember to always wear protective clothing, including a head net.
Treating the nest with an insecticide is an effective way to control wasps. Spraying after nightfall is recommended because wasps are less active at night. Do not use a light directly on the nest because this will alarm the wasps and increase their activity. Use a red filter over your flashlight to provide visibility without increasing wasp activity. Always wear appropriate protective clothing when using pesticides.