The total production of progeny by a single female of a tachinid,Eucelatoriasp., when species ofHeliothiswere used as hosts ranged from 144 at 20°C to 198 at 30°C and declined at temperatures above 30°C. The mean number per female rose from 68.2 at 20°C to 112.9 at 30°C and then dropped to 52.4 at 32.2°C and to 2.0 at 35°C. Mean female longevity declined from 61.8 days at 20°C to 17.9 days at 35°C. Males were 7–10 days shorter lived over the same temperature range.