none The developmental cycle and the number of progeny produced by Apanteles muesebecki Blanchard, 1947 were studied in the laboratory at 20 degree C and 25 degree C. Host instar preference and the occurrence of parthenogenesis were determined for larvae of Pseudaletia sequax Franclemont, 1951 at 25 degree C. The developmental cycle of A. muesebecki when oviposition took place into the 2nd. instar of P. sequax was proportional to the time required for the host to complete its larval development; emergence of the parasitoids from the host was always during the last (6th.) instar. The period between oviposition and emergence of larvae from P. sequax was 23.4 +- 1.15 days at 20 degree C and 16.5 +- 0.80 days at 25 degree C. The prepupal and pupal stages took 12.7 +- 0.79 days and 7.7 +- 0.60 days at 20 degree C and 25 degree C, respectively. The number of pupae/host was 130 +- 61.3 at 20 degree C and 98 +- 37.7 at 25 degree C, with pupal mortalities of 16.5% and 12.2%, for the two temperatures.