The contents of this paper indicates that weather has a marked effect on barkbeetle outbreaks. A hickory barkbeetle, Eccoptogaster quadrispinosus , outbreak occurred during the drought period of 1925 in North Carolina. The marked deficiency in precipitation weakened hickory trees by checking growth and rendered them attractive to beetle attacks, favoring brood development. An excess of precipitation during periods of beetle flight resulted in a partial mortality of the adults, thereby considerably reducing the number attacking and also rendered trees unfavorable for brood development.