Bethylidae 513 



freshly spun larvae of the fruit moth, [see p. 345.] Several other hosts 

 were tried, none of which gave desirable results. One pair of parasites 

 is placed in each vial without host material for a period of 5 days in order 

 to permit mating and to complete the pre-oviposition period. Finally, a 

 single fruit moth larva, spun in corrugated cardboard, is exposed to each 

 female for 24 hours at a controlled temperature of 76 F. and 60% rela- 

 tive humidity. Parasitized larvae, when removed from the parasite con- 

 tainers, are placed in vials similar to those employed for rearing purposes 

 except that there is no raisin present. These vials are held at the fore- 

 going temperature and humidity until the adult parasites emerge. The 

 latter are then refrigerated at 50 F. and 80% relative humidity to 

 await colonization. 



The immature or larval development of the parasites is passed con- 

 cealed in the cocoon of its host. Likewise, the pupal stage is completed 

 in this matter. However, occasionally a larva may, during its prepupal 

 stage, work its way to the exterior of the host cocoon before forming 

 its own cocoon in preparation for pupation. Males complete their de- 

 velopment in slightly less than 12 days, whereas females require a few 

 additional hours, extending their emergence into the twelfth day. The 

 optimum period for both sexes is from 12% to 14 days. Adult 

 Perisierolas may remain in their cocoons for some time following the 

 appearance of exit holes. Notwithstanding, males manifest a proclivity 

 for visiting females before the latter leave their cocoons. Occasionally 

 these visits result in successful mating prior to cocoon evacuation. The 

 initial fertilization is sufficient to fecundate females for the entire period 

 of reproduction which generally extends intermittently throughout their 

 life. Males survive for a much shorter period than females, the average 

 being from 12 to 16 days. Female longevity averages 40 days with a 

 maximum of four months. 



The parasite paralyzes its host by stinging prior to parasitizing. The 

 number of eggs deposited on a single host of the size of the fruit moth 

 larvae varies from 1 to 14, averaging about 4 to 6. The incubation 

 period of the eggs under controlled conditions is from 36 hours to two 

 days and the larvae feed from the exterior of the host for 3 to 4 days 

 before pupating. Thus the cocoon and pupal stage of the parasite in- 

 cludes more than half the life cycle of the species. The sex ratio is 

 approximately one to one. 



REARING LAELIUS ANTHRENIVORUS 



Arlo M. Vance, U. S. Bureau of Entomology and Plant Quarantine 



THIS parasite was handled in a warm laboratory room. Each female 

 was placed in a small glass globe cage containing some dry insect 

 material upon which Anthrenus larvae of different stages were feeding. 



