Timing: Place dispensers in the field before beetle flight. Expected longevity of the dispensers is 50-60 days depending on weather conditions. Apply product before beetles begin to fly and attack trees in the Spring for maximum effect. If it is applied early in the flight season, but after beetles have initiated attacks on a few trees, it may still reduce the number of trees that are killed within the treated area. Beetle flight in a typical year occurs late April to early May. Hercon Disrupt MCH applied by the third week in April should be effective in protecting trees and will last throughout the beetle flight. A second treatment is recommended during an extended beetle flight.