none Seasonal occurrence of Apanteles sp. group ultor during three winter seasons (1983-1986) showed that October eggs developed normally to wasps within October-November after accumulate 202 to 374 D-D. Sibling differences in development were noticed in populations, in which the egg development started during November-December. Some of internal phase developed to pupae and accumulate 208-263 D-D. These pupae died due to cold conditions "under base temperature" (ubT) while other internal phase entered diapause during December to March then developed to pupae and accumulate 284-378 D-D. Daily minimum temperatures less than 11.2 degree C cause diapause induction. Post-diapause development begins at April when daily minimum temperature is higher than 11.2 degree C. Pupae facing cold weather lower than ubT failed to produce wasps. Life cycle and development; Development; Metamorphosis; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Abiotic factors; Physical factors Ectomyelois ceratoniae (Pyralidae); Emergence from pupa; Hymenopteran parasite development & temperature relationships; Hymenopteran parasites; Apanteles ultor species group; Parasite development, relations with temperature & host development; Temperature; Emergence patterns relationship Apanteles ultor species group (Braconidae); Development; Thermal requirements & relations with lepidopteran host development; Lepidopteran hosts; Ectomyelois ceratoniae; Parasite development, relations with temperature & host development; Temperature; Development relationship, lepidopteran host