Seasonal Variations in Activity of the Southern Pine Beetle in East Texas

Abstract

In southern pine beetle, Dendroctonus frontalis Zimmerman, populations in east Texas during 1960-62, average ratios of increase were 2 or 3 to 1 for each generation during the late fall through early spring. During June through September they were less than 1 to 1. Number and size of new infestations increased most rapidly during April, May, and June. Beetles attacked upper stems during the cooler months, the lower third of stems in midsummer. Changes in attack intensities, host conditions, and abundance of natural enemies seemed to account for much of the seasonal variation in brood establishment and development. During midsummer prolonged high temperatures apparently limited dispersal and survival. Artificial control measures should be intensified in fall, winter, and early spring.