Ecological and Experimental Study of Sarcophagidce 67 



factor which requires a hasty consumption of the flesh is the dry- 

 ing out caused by the sun, and also the decay from putrefaction. 

 The above general observations led to the following described 

 systematic experiments bearing on the subject of correlation with 

 food supply. 



V EFFECTS OF OVER AND UNDERFEEDING 



The observations described in the last chapter were interpreted 

 to mean three things, viz: First, That there exists an optimum at 

 which a certain larval weight is reached, which is the weight best 

 adapted to pupation and emergence as imagines. Second, That if 

 feeding is carried on beyond this optimum point, pupation is hin- 

 dered or even death may ensue. Third, There must be a point 

 beloiv the optimum at which the larvae can barely pupate, and 

 have not strength enough to carry through the pupal period or will 

 even die before pupation. To determine the facts and to find the 

 critical point between death or survival, the series of experiments 

 about to be described was arranged. 



On August 12, 1905, a large German carp, quite fresh, was 

 washed up. This carcass was immediately taken from the beach, 

 placed near the laboratory and exposed for eggs of Lucilia caesar. 

 In an hour and a half (between 10 and 1 1.30 o'clock, a. m.), about 

 eleven thousand eggs were deposited, the gross weight of which 

 was 1083 mg. The fish was taken into the laboratory, the viscera 

 removed, the body cut into six pieces, and the eggs roughly divided 

 into six masses. These masses were then placed upon the pieces, 

 which in turn were placed in separate boxes or compartments. 

 Two of these sets were used for histological material, and conse- 

 quently only four series (series i, 2, 3, 4) were used in the experi- 

 ment. The eggs hatched early August 13. The plan was to 

 take the flesh away from a portion of each set at consecutive inter- 

 vals of six hours each, allowing one series to migrate normally, 

 weighing the larvae at end of feeding period. Then the weighed 

 larvae were placed in separate dishes so that the same lot could be 

 weighed again about the middle of the period of pupation, and 

 the adults when the wings and bodies were dry. The remainder 

 of each series was retained as a check or in case of accident. 



