By Joerg Schmidt-Bailey, Integrated Pest Management Educator, University of Illinois Extension Countryside Center
Reprinted from The Illinois Fruit and Vegetable News, Vol. 7, No. 6 April 25, 2001
Unlike honey bees (Apis mellifera), which winter as an entire colony containing thousands of individual bees, yellowjacket wasps (Vespula vulgaris, Vespula germanica) do not winter as colonies. Only mated yellowjacket queens survive winter in a hibernating state, hidden in protected places such as soil cavities, leaf litter, compost piles, hollow logs, under bark, stumps, firewood (remember this when you bring it inside!) and behind wall siding. They start hiding in these places around November and will stay there until the temperatures start to become spring-like in April. Then the queens, which are about 3/4 of an inch (19mm) long, with alternating black and yellow stripes on their bodies, emerge, feed on insect prey and nectar sources and start looking immediately for a new nest-site. Potential and preferred sites include uninhabited rodent burrows, clustered tree branches, dense shrubs, garages, sheds, attics, spaces behind wall siding, under eaves on buildings, under porches, and inside buildings in hollow walls and floors. After they choose a site, the queens start building a little paper-like nest using weathered wood, bark and their own saliva. The initial nest contains no more then 40-50 cells in which the queen lays one egg per cell. It takes around a month for the eggs to turn into adult worker wasps. During the summer month the nest will grow to a population of several thousand individuals.
It is with good reason that I described the behavior of the yellowjacket queens and their initial nest building in such detail - because it is exactly the biology of the yellowjackets which allows you to easily and efficiently control them in early spring around your house. You only have to deal with a single wasp, and you have a whole month to do so before the nest begins to grow. Here are a few pointers on yellowjacket control:
- Tour and scout your property regularly in early spring for potential nest-sites and yellowjacket queens on their "nest-hunting" flights.
- Fill rodent burrows with soil, check the siding of your house, garage and shed for openings and cracks and fill them or apply wire screen to prevent the queens from entering. Wire screen also works well for porches and on attic ventilation openings. And it will protect you for more than just yellowjackets!
- If you encounter a queen that has already started its initial nest, get the fly swatter out, kill the queen and remove the nest. Not the other way around, because the queen will defend the nest! If you are not brave enough to do it (it is only a single wasp, but I know they are quite intimidating), you can place a few commercial yellowjacket traps close to the locations on your property where you want to prevent nest building. These traps use either a wasp specific smell (pheromone) or the smell of food to attract and trap them.
This article originally appeared in the May 11, 2001 issue, p. 55.
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