Extension Service Garden Hints

Life's a picnic for yellow jackets this time of year

CORVALLIS - Now that summer is in full swing, yellow jackets are beginning to appear at your picnic. Who are these uninvited guests, and what can be done about them?

There are several different kinds of yellow jackets in Oregon, according to OSU entomologist Jack DeAngelis. Not all will crash your barbecue. Some are forest species. Many prey strictly on other insects such as houseflies and mosquitoes.

The most common picnic-crashers are the western yellow jacket and the common yellow jacket. Both are scavengers and both have an eye on your hamburger.

These species live in paper-lined underground nests. A queen begins nest-building in the spring. She hatches out a starter set of workers, and never leaves the nest again. Her role now is to lay eggs. By the end of the summer, yellow jacket nests may contain thousands of workers vigorously defending their nest and queen. This is when they are most troublesome and dangerous.

Unlike honeybees, yellow jackets don't store food in their nests. They hunt for the food they need as the nest develops. During the early summer months, yellow jacket workers seek out meat-based foods to feed the developing young. Later in the summer, yellow jackets' tastes switch to sweets. They begin to search out rotting fruit and sugars.

By August or September, nest development turns toward creating queens and males. By October, the new fertilized queens fly off to find a protected spot to spend the winter. Those males and the workers that kept the nest humming all summer will die with the first frosts. Only new queens survive the winter.

The old nest is abandoned and not reused the following spring.

So the nest you find now will be dead in a few months, which may be little comfort to your picnic guests this summer. Traps can provide some relief by temporarily drawing the yellow jackets away from your picnic table. Worker yellow jackets are lured into the trap by the smell of food and can't find their way out. Synthetic baits are most effective, but you can also use meat or fruit juice as bait.

If you find a yellow jacket nest in your yard, DeAngelis offers some advice for its removal:

First, consider if it is a hazard. Most nests pose little threat unless you interfere with them.

If you decide to spray, use only an approved wasp and hornet spray. Read the label, it is the final word on what does or does not constitute a legal and safe application.

Treat nests at night when all workers are inside and relatively calm.

DO NOT pour gasoline into ground nests - it is dangerous, environmentally harmful and illegal.

You can find more information about yellow jacket control and the use of special poison bait from the OSU Extension website on Urban Entomology. Find it at http://www.ent.orst.edu/urban/home.html.

By: Peg Herring
Source: Jack DeAngelis

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