Dispersal. Fill a 30-foot-long segment of vinyl guttering with coarse. Moist sawdust to a depth of about 3-4 cm. and apply a very thin film of petroleum jelly to the inside upper edge of the sides and ends. Prepare a colony of files, either by allowing oviposition on a ball of meat with several hundred growing larvae. Mark each parasitized pupa with a dot of white typewriter correction fluid so that it can be distinguished from dispersing larvae. After dispersal is complete and pupa had occurred remove the sawdust from 0.1-m