TRAPPING YELLOWJACKETS (HYMENOPTERA: VESPIDAE) WITH HEPTYL BUTYRATE EMITTED FROM CONTROLLED-RELEASE DISPENSERS

Abstract

Numbers of workers of Vespula pensylvanica (Saussure) (western yellowjacket) and V. atropilosa (Sladen) trapped with heptyl butyrate in Washington increased with greater release of the attractant from vial dispensers, up to an estimated 2.3 milligrams heptyl butyrate per hour. Vespula germanica (F.) (German yellowjacket) workers were also captured in significant numbers, and numbers of workers captured increased with increased release of heptyl butyrate, up to an estimated 1.4 milligrams per hour. Numbers of workers of Vespula squamosa (Drury) trapped with heptyl butyrate in Oklahoma increased with increased release of heptyl butyrate from dispensers, up to an estimated 3.3 milligrams per hour. Vial dispensers, with holes of 6, 12, 22, and 33 mm diameter in the vial lid, lost 0.42, 1.4, 2.3, and 3.3 milligrams of heptyl butyrate per hour in the laboratory and these rates changed little over a period of 4 weeks, indicating close to a zero order rate of release pattern. Rates of loss of 2 ml heptyl butyrate applied to a cotton ball decreased with exposure time, from an initial rate of 6.0 milligrams per hour to near zero at 16 days post-treatment. Captures of wasps in traps sold commercially might be improved with the use of a controlled-release dispenser.