Ecological and Experimental Study of Sarcophagidce 6i 



is followed during the next two hours by an average decrease of 

 17.5 per cent. This decrease was shared by three sets, and two 

 further sets showed zero growth, which was probably due to the 

 fact that the weighing was done a half to three-quarters hour 

 later, during which time the larvae gained enough to bring the pro- 

 cess from negative to zero. Neither does the sixth set show the 

 decrease because it was weighed still later. Five of the six sets 

 of Lucilia were thus affected, as is shown by Table I.^ 



o I 2 3 4 5 6 7 S 9 10 II 12 13 14 15 16 



Fig. 2 Growth curve of Lucilia caesar Linne, derived from Table II, column 4, on the basis of 10 

 individuals; a: = days; y = milligrams. The dotted line at the beginning of the curve represents the 

 egg stage; the solid line represents the larval period with the apex as the point of migration; the broken 

 line represents the period of pupation and the drop at the end, the loss of the pupa cases. 



Migration is represented by the apex of the curve when the 

 larvae reach an average weight of 40.4 mg. and this for a feeding 

 period of about sixty hours (57+hours), an average hourly in- 

 crease of .7070 mg. or an increase of 40,400 per cent of the orginal 

 weight. 



Immediately after migration there is a marked loss in weight. 



'Loss of weight probably due to loss of moisture in crawling on dry surface of receptacle. 



