ON THE DELAYED PUPATION OF THE FLESHFLY, SARCOPHAGA PEREGRINA ROBINEAU-DESVOIDY

Abstract

The larvae of Sarcophaga peregrina do not pupate in a wet condition. If they are placed in a glass vessel containing a certain amount of water, their pupation delays for 100 hr or more. The cause of this delayed pupation is neither a direct action of water to their integument nor disturbance of respiration, because the pupation takes place even in a wet vessel, if they have been previously exposed to a dry situation for a certain period.
The mature larvae transferred into a dry vessel from a wet one always pupate 18 to 24 hr later. Ligation experiments show that the hormone inducing the pupation is released 6 hr after transference to a dry condition. When the ligation is made in the middle of the animal, behind the brain and the ring gland, the hind part of it readily pupates by an injection of ecdysone. The results of these experiments suggest that retardation of ecdysone release is the final reason for the delayed pupation. It seems likely that their removal from water contact induces the secretion of ecdysone from the ring gland.