CONTROLLED PUPATION 445 



void of feet. They feast like gluttons upon the nascent flesh 

 of the ripening fruit until it comes time to pupate. 



From what we know of many other flies, we have seen 

 that it is natural for them to pupate within the ground, or 

 at least in a position from which they may work their way 

 to the light of day when nature has transformed them into 

 perfect insects. The larval flesh fly burrows below her car- 

 rion to transform in the damp soil beneath, the house fly in 

 its bed of manure finds escape an easy matter, the mosquito 

 transforms in the water, but what of our flies born within a 

 tough-shelled nut, in the highest forest branches? How are 

 they to release themselves from such a prison after the feast 

 is over? As we have seen, they reach the ground by falling, 

 when the nut is plucked by some roaming monkey or as it 

 falls anyway when ripe, carrying its living burden earth- 

 ward. But that is not answering the question. The larvae 

 must burrow into the forest soil to transform and issue suc- 

 cessfully as a perfect insect. How then is this feat accom- 

 plished ? 



The nut which I cut open contained eleven larvae. 

 They appear to be full grown and ready to pupate, at any 

 rate there is no more pulp left for them, and if they are hun- 

 gry they must eat again that which has already been digested 

 once. No, they simply wriggle about frantically, as though 

 searching for an opening, and swarm to the hole I have cut. 



I remove two of them to tubes of soil slightly dampened. 

 The remainder are locked once more in their prison. In the 

 tubes conditions are, as near as I can make them, like those 

 of the forest floor. The larvae move here and there from 

 fright in their new environment for a minute or two, but 

 presently one thrusts its pointed head into the soil and com- 

 mences to burrow. Soon it is followed by the other larvae 

 in their respective tubes. In twenty minutes all have disap- 

 peared below the surface. 



Two days later I remove the material from the tubes in 

 search of the larvae. They have burrowed slightly over half 



