Monday, August 31, 2009

Landscape - European Hornets Out Now

European hornets are now active in Delaware landscapes feeding on ripe fruits. The following is more information on this insect.

The European hornet is a large wasp resembling a yellow jacketsbut much larger. The European hornet is about 35 mm (1.5 inches) long and is brown with yellow markings. Nests are rarely constructed in open areas and are more likely to be found in protected areas such as tree cavities, bird houses, barns, or sheds. During the summer, these hornets feed on large insects such as caterpillars, grasshoppers, flies, and bees. European hornets damage a number of ornamental trees and shrubs including, lilacs, rhododendrons, birch, ash, and dogwood. The hornet gains nourishment from the plant sap and the bark may be used as nesting material. Workers expand the nest throughout the summer, and in the fall the next season's queens mate with newly emerged male hornets. European hornets feed on substances high in carbohydrates in the fall. These food sources include overripe fruits, tree sap, soft drinks, juices, and possibly honeydew produced by insects such as aphids or scales. This hornet is also known to attack small fruits such as grapes and consume the sugars. European hornets do not reuse nests and populations die off with the onset of cold weather. The only effective method of control is nest removal. A pressurized wasp and hornet spray with a range of 10 15 feet is desirable. Treatments should be made at dusk or after dark to ensure most of the hornets are in the nest. Caution should be used when treating hornet nests since hornets guard the nest, can sting repeatedly, and can fly at night.

European Hornet. Photo by Jessica Lawrence, NC State Entomology Department,

Information from Brian Kunkel, Ornamental IPM Specialist, UD

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