284 THE WONDER OF LIFE 



Riley discovered that there were two comraon insect 

 visitors, that came and went and were not destroyed. One 

 of these is a flesh-fly {Sarcophaga sarraceniw), which is 

 attracted by the odour of putrescence and deposits its 

 maggots (it is viviparous) in the rotting material, with 

 remains of ants, flies, moths, beetles, katydids, crickets, 

 and the hke, at the bottom of the pitcher. 



The whitish maggots riot in the putrid insect remains, 

 but, of the dozen or so that there are to start with, ' usually 

 but one matures, even when there appears macerated food 

 enough for several '. A fratricidal warfare is waged which 

 reduces the numbers in this remarkable way. When the 

 survivor has attained its full larval size it bores through the 

 leaf and burrows in the ground. After a few days' pupation 

 it issues as a large two-winged fly. Two questions natur- 

 ally present themselves. Why the adult escapes the fate of 

 all but one of the other insects that enter or tumble into 

 the tube 1 and Why the maggot is not killed in the noxious 

 fluid in which it revels ? 



The fly is probably safe because it has strong, spreading 

 legs with large adhesive surfaces and strong claws, which 

 enable it to get a grip of the cellular tissue of the pitcher 

 surface in spite of the slippery downward-projecting hairs. 

 When it is disturbed within the pitcher it buzzes about 

 violently and emerges in most cases successfully. It is 

 more di£&cult to explain the survival of the maggots, ex- 

 cept by simply pointing to other cases where dipterous 

 larvae Kve in what seem to be hazardous situations, e.g. 

 inside the food-canal of a higher animal or inside decaying 

 matter. 



The other intruder, who successfully braves the dangers 

 of the trap, is a little glossy moth, marked with grey-black 



