Ecological and Experimental Study of SarcophagidcB 65 



tends to be followed by an opposite compensating irregularity. 

 Second, The variability diminishes with the age," also, "the 

 irregularity of growth of an individual is very great" and "each 

 individual strives to reach a particular size." As a proof for this 

 latter statement, see Table I. The average weight of migrating 

 Lucilia larvae for the five sets shown is, viz: 38.6, 40.4, 39.4, 36.0 

 and 39.0 mgs. 



0123 4567 8 9 10 II 12 13 14 15 16 17 18 19 

 Fig. 5 Growth curve of Sarcophaga sarraceniae Riley, based on percentage increments, derived 

 from Table III, column lo; x = days; y = percentage increments. Crosses represent point of migra- 

 tion and point of pupation. 



IV CORRELATION OF FEEDING PERIOD WITH FOOD SUPPLY 



That there exists a correlation between the feeding period of 

 the larvae and the food supply, there can be no doubt. My atten- 

 tion was called to this fact time and again. To illustrate, one 

 instance follows: On July 28, 1905, a fish was exposed for fly 

 eggs and about one thousand were secured between 1.45 and 3.45 

 o'clock, p. m., not a large number. The eggs were distributed 

 over several pieces of the flesh, the larvae emerging early July 29. 

 As early as noon of July 31 (54 hours feeding), the larvae on the 



