**8. Conclusions**

The results of the many studies presented in this chapter indicate that preventative applica‐ tions of insecticides are a viable option for protecting individual trees from mortality due to bark beetle attack. Bole sprays of bifenthrin, carbaryl and permethrin are most commonly used. Several formulations are available and effective if properly applied. Residual activity varies with active ingredient, bark beetle species, tree species and associated climatic condi‐ tions, but generally one to three years of protection can be expected with a single applica‐ tion. Recent advances in methods and formulations for individual tree injection are promising, and further research and development is ongoing. We expect the use of tree in‐ jections to increase in the future. In general, preventative applications of insecticides pose little threat to adjacent environments, and few negative impacts have been observed. We hope that forest health professionals and other resource managers use this publication and other reports to make informed, judicious decisions concerning the appropriate use of pre‐ ventative treatments to protect trees from mortality due to bark beetle attack. Additional technical assistance in the U.S. can be obtained from Forest Health Protection (USDA Forest Service) entomologists (www.fs.fed.us/foresthealth/), state forest entomologists, and county extension agents (www.csrees.usda.gov/Extension/). We encourage use of these resources before applying any insecticides to protect trees from bark beetle attack.
