none Experiments were conducted to determine the life history, fecundity, longevity, and developmental period of A. pyralophagus Marsh, a gregarious, external parasite of Mexican rice borer, E. loftini (Dyar). Female parasites oviposited on larval hosts in tunnels after drilling through plant tissue and paralyzing the host. Mature larvae pupated inside the tunnel and adults escaped through the tunnel entrance. Fecundity averaged from 68.0 to 82.3 eggs per female in the temperature range 20-32 degree C, and no eggs were laid by 1-day-old females. Median life span for ovipositing females was 57.4, 24.0, and 32.5 days at 20, 26, and 32 degree C, respectively. Development from egg to adult required 17.75 days at 26 degree C at a density of five parasites per host.