Bracon hebetor Say (Hymenoptera: Braconidae) is a gregarious synovigenic parasitoid that attacks late stage larvae of many important lepidopterous species. The purpose of the current study was to evaluate the influence of 3 constant (18, 25, and 35 degrees C) and 1 alternating temperature (incubator programmed to vary daily between 18, 25, and 35 degrees C at 8 h intervals) on protein and lipid amounts of female and male parasitoids. Protein amounts of female parasitoids were highest when exposed to alternating temperature. At all the temperatures tested, 1-day-old males had similar amounts of protein, but 5- and 10-day-old males had higher amounts of protein at alternating temperature than at other temperatures. One-day-old females had slight fluctuations in lipid levels depending upon rearing temperature, but no consistent trend was found resulting in either increasing or decreasing between these values. In 1-day-old males, lipid levels were significantly lower at 18 and 25 degrees C than at 35 degrees C and alternating temperatures. B. hebetor adults reared at different temperatures were found to utilize their original lipid reserves during the first 10 days of adult life.