none The number of Heydenia unica C. and D., Spathius pallidus Ashm., Dendrosoter sulcatus Mues., Meteorus hypophalaei Cush., and Coeloides pissodis Ashm. arriving at southern pine beetle infested trees fluctuated with period and year. Most female H. unica and C. pissodis arrived 21-30 days after the initial attack by southern pine beetles; most S. pallidus and D. sulcatus arrived 20-25 days and 16-30 days, respectively, after the initial beetle attack. Female activity of all the parasites was both diurnal and nocturnal. Most diurnal activity of H. unica and D. sulcatus occurred between 0900 and 1300 h EST, while C. pissodis females were active all day. Diurnal activity of S. pallidis peaked before 0730 h and after 1800 h EST. Most nocturnal activity of H. unica, C. pissodis, S. pallidus , and D. sulcatus peaked between 2100 and 2230 h. Female D. sulcatus were active all night.