none Diachasmimorpha longicaudata; SPERM-; MATING-; Copulation interval effects on sperm competition & mating observations; INTRASPECIFIC-COMPETITION; Sperm competition, effect of interval between copulations Sperm competition was studied in the parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) with a genetically marked stock. Females mated more than once. The spermatozoids partially mixed within the spermatheca of the female when the interval between two matings was lt 6 min. The second mating male sired a mean progeny proportion (P-2) of 0.49. At the beginning of the oviposition period, the spermatozoids of the second mating male were released; those of the first male were released at the end of the oviposition period. Apparently the time period between the first and second copulation influences P-2 because copulations with an interval of 24 h resulted in P-2 simeq 0.75. Some observations on the mating behavior are also described.