P&PDL Picture of the Week for
August 23, 2004

Wasp nest? Let it be may be the best answer!

Tim Gibb, Insect Diagnostician, Department of Entomology, Purdue University

Several species of wasps, including paper wasps, yellow jackets and hornets construct gray, paper-like nests made up of wood or foliage chewed up and elaborated by the insects. Regardless of the species, all colonies of these wasps have two things in common; (1) they can sting very effectively and (2) they are beneficial insects because they eat spiders and other insects that are potential pests. These two seemingly opposite characteristics make the call on 'should I destroy the wasp nest in my yard or let it be?', a difficult decision.

Certainly, nobody wants to be stung by a wasp. A wasp nest that is found in a place where there is a likelihood of humans bumping into or getting very close to the nest should be removed. This can be done by professional pest managers or with the use of wasp killing, aerosol chemicals designed to be sprayed from a distance.

On the other hand, a nest that is found to be high in a tree or under the eaves of a home can usually be left alone without any adverse results. Just alerting people to the location of the nest, so that they are aware of its presence, is usually enough warning to prevent accidental encounters.

By leaving the nest alone a homeowner can decrease the danger of being stung while trying to kill the wasps, save on the chemical cost of controlling it, and increase the natural pest control in the yard. In cases where the nest is located in a wall void or in a building, by leaving the nest alone, a homeowner can save the costs of breaking into the wall to remove the nest. After the wasps have been killed, large nests containing food stores as well as immature larvae soon begin to rot and stink if not removed. Additionally, other insect and rodent pests may be attracted to the dying nest.

Most home owners do not realize that wasp nests are cleaned out each fall by the wasps themselves. The empty nests contain nothing but the outside paper shell at that time. This too will break down and disintegrate through the winter. Wasps never re-use the same nest from season to season, so letting mother nature take care of them through time, is usually the best control method we have.

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Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service