The present report concerns the relation of mating of Pseudaphycus malinus Gahan, an important parasite of Pseudococcus comstocki (Kuwana) to the sex of the progeny. All experiments were made at the temperature of 25℃. The number of female parasite was more numerous than that of male, the percentage of female having been about 70. The reproduction of this parasite is arrhenotokous parthenogenesis. But the male parasite emerges much earlier and lives longer than the female. This characteristic tendency of the male parasite suggests a possibility that the parasite is able to mate easily even when the number of male is less than that of female. Most of the parasites finish mating during 24 hours after their emergence. The number of progeny produced by an unfertilized female in the present experiment was less than that by a fertilized one. There would be no substantial difference in the number of progeny between the fertilized and unfertilized females.