Chemical Controls

Timing of Treatments
Treatments are most effective if they are initiated before adelgid populations have reached detrimental levels and tree health has been compromised. Chemical treatments are most effective in the spring or fall, and should be avoided in freezing weather.

A number of insecticides can be effective in controlling HWA. Depending on the application technique, they must be repeated at intervals ranging from several months to several years. Some insecticides such as pyrethrums are effective against adelgids but kill beneficial insects such as predatory mites and could prevent establishment of specialist predator beetles being released for biological control of HWA. Read and follow the instructions on the pesticide label before using any treatment to ensure compliance with all laws in order to protect the applicator and the environment. Some pesticides may only be applied by a licensed pesticide applicator.