European Hornets Invade Ozarks

The European Hornet is the largest of the vespid wasps in North America, growing to 1.5 inches in length. It's the only wasp that is brown with yellow markings, says Richard Houseman, entomologist at the University of Missouri-Columbia.

Staff at the University Outreach and Extension Office in West Plains received more than a dozen calls last month from Ozarkers alarmed about--and stung by--these hornets.

Colonies are typically the largest and most active in the late summer months. While hornets are not as aggressive as other wasps and normally don't sting unless provoked, they will defend their colonies, Houseman said.

This pest is not new to the country. European Hornets arrived in New York around 1840 and are found throughout the eastern United States and Canada.

They prefer forested areas like the Ozarks. Their nests are usually paper-like combs that are brown in color, distinguished from the gray nests of Baldfaced hornets.

``They came over on a ship in the 1800s and have been migrating west for years,'' said Randy Saner of the Extension Office. ``They are big and exotic looking, and we have received more calls this summer from concerned people than we ever have.''

The reason for that, Saner suspects, is the increased construction in forest areas.

``I have a feeling these hornets have been around here for years,'' he said. ``But since we have seen an explosion of new homes and construction in the country, there has been more human contact with them than ever.''

Despite their reputation, European hornets are actually beneficial insects, says Houseman. They capture caterpillars, grasshoppers, flies and other wasps.

But they also attack honeybees and will eat ripening fruit. The large wasps can also damage landscape trees and shrubs, chewing the bark from twigs as they seek sap.

Houseman recommends that the hornets not be exterminated unless absolutely necessary. If they must be controlled, the nest must be destroyed--an endeavor best left to professionals.

For the do-it-yourselfers, Houseman recommends working after dark when the wasps are in the nest, using veils and a flashlight with red cellophane over the lens. Chemical products, called wasp freezes, can also be used to send a pressurized stream of insecticide into the nest opening from 15 feet away.

Houseman warns that the entrance hole of the nest should never be plugged--unless you want some new roommates.

``The hornets may chew a hole into the living space of the house,'' he said.

Large colonies may reach a population of 1,000 during the summer. However, all except the newly formed queens die at the start of winter. These queens build small nests and start new colonies the following year.