What Do They Look Like?

yellowjackets 166x166 sqYellowjackets are smooth, yellow and black, striped wasps, about two centimetres long. They live in colonies with a queen in large, oval nests they construct of wood fibres. Nests look like papery grey balls and may be attached to the eaves of buildings, undersides of decks, tree branches or other sites (some yellowjackets also nest in the ground).

Yellowjacket Life Cycle

In the spring, the queen starts a small nest, lays a few eggs and rears the first generation of worker wasps herself. They take over collecting food and feeding later generations of larvae. As the colony increases, the wasps add more layers to the nest. The queen stops laying eggs in late summer. All of the wasps, except the queen, die off in the fall. The queen over-winters in a hiding place under bark, in woodpiles or other debris.

When Are Yellowjackets A Problem?

Yellowjackets sting to defend their nests and can be dangerous to people allergic to insect venom. They are also beneficial predators of caterpillars, house flies and other pests. Whether yellowjackets are a problem depends on how close a nest is to places frequented by people and whether someone allergic to stings is likely to be at risk. Yellowjackets are very common in some years and comparatively rare in others. Yellowjacket populations are highest in late summer, just when they are most likely to be a nuisance at outdoor picnics. The wasps all die off by October and do not use the same nest the following year. Therefore, if you can live with a nearby nest for the rest of the season, there is no need to take action.

How Do I Prevent Stings?

Pick fruit early in the morning, or even at night, while it is cool and wasps are less active. Remove all outdoor food sources that attract wasps: feed pets indoors, keep garbage cans tightly closed, collect over-ripe or dropped fruit and bury it deeply in the compost pile. Keep picnic foods indoors or tightly covered until the moment you eat. Serve drinks in covered cups and use straws to drink from cans. Divert wasps from picnics and barbeques by setting out a couple of opened cans of cat food, well away from the eating area.You can collect the can after dark, when the wasps have left. Before a picnic you can also set out a couple of the re-useable wasp traps sold at garden centres. Use bait supplied with the trap or your own baits. Meat baits (canned meat, cat food or fish) are more attractive for most of the summer, but in late August sweet baits, such as juice or rotting fruit can be more attractive. Where yellowjackets are attracted to aphid honeydew on trees, spray the foliage with water to clean the leaves.

What Can I Do To Control Them?

Yellowjackets fly for several kilometres from their nests, therefore you will not be able to eliminate all risk from yellowjackets. You may want to remove a particular nest that is too close to a high-use area. The safest approach is to hire a professional pest management service to remove a nest. This is especially important for nests high off the ground or in hard to reach locations. If you really want to remove a nest yourself, do it as early in the summer as possible, while nests are small. Here’s how: Have someone help you and do the work in the evening when wasps are less active. Wear protective clothing, including a hat (preferably with a veil, such as used by beekeepers), safety goggles, a long-sleeved shirt, pants and gloves. Make sure you and your helper are well-covered from head to toe! Have your helper hold a large bag or box open under the nest, while you cut the nest attachment with a long-handled pruner or other tool. Quickly seal up the container with the nest inside. Put the container in a freezer to kill the wasps or direct a wasp spray containing pyrethrins into the bag and reseal. Don’t leave wasps alive for long in the container as they can chew their way out

Tips For A Healthy Garden

  • Enrich the soil once or twice a year with compost or other organic fertilizers.
  • Choose plants adapted to the conditions of sun or shade, moisture and soil acidity. If necessary, correct the drainage and acidity to suit the plants.
  • Plant native plants, which are adapted to the local climate. Most are easy to care for and have few pest problems.
  • Before buying plants, make sure they are healthy and free of diseases and insect pests.
  • Water deeply, but infrequently, to encourage deep rooting.
  • Cover the soil between plants and under shrubs with organic mulches. This insulates the soil, keeps in moisture and suppresses weeds.
  • Protect and attract native beneficial insect, birds and other animals.
© Image courtesy of E. Cronin

Yellow Jackets Fact Sheet

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