none Biological studies of the external, gregarious braconid Rhaconotus roslinensis Lal were conducted using Texas (USA) sugarcane pests Diatraea saccharalis (F.) and Eoreuma loftini (Dayar) as hosts. Optimal temperature for immature development and survivorship was 26 degree C, with a total developmental time of 19.3 days and 15.8% mortality of eggs and immatures. Lower threshold for development was near 20 degree C, with only 13.4% survivorship at that temperatures. Honey-fed females lived 41 days at 26 degree C. LiIfe tables generated on the two host species indicated that although R. roslinensis successfully developed on both hosts, D. saccharalis was more suitable. Increasing numbers of parasite larvae developing on a host affected larval coccoon-spinning behavior and significantly reduced developmental time, survivorship, and the size of subsequent adults. However, there was no interaction between amount of food available to parasite larvae, parasite adult size, and total number of competing larvae, such that large clutches provided with a specific amount of food gave rise to larger adult parasites than did small clutches provided the same amount of food. This effect reduced the impact of intraspecific component and was an adaptation to a gregarious feeding strategy. The mechanism for this effect was hypothesized to be the injection of predigestive enzymes into the host by feeding parasite larvae.