Ecological and Experimental Study of Sarcophagidce 63 



seems to disintegrate, forming a mass of fluid matter, but in the 

 third day there is a rapid organization, which results in an indi- 

 vidual that could be easily recognized as a fly, even at this early 

 period. 



All pupae were kept in glass vials about two-thirds full of sand 

 in which they were buried. These vials were covered with netting 

 (bobbinet), and were kept near a window which was kept open 

 most of the time together with other windows in the room. That 

 the sand, which was comparatively dry, might extract moisture 

 from the air and in turn transmit it to the pupae is very probable. 



The increase in weight above mentioned is followed by a nearly 

 corresponding decrease during the next twelve hours, which re- 

 sulting weight is held for two days and a half. At the end of this 

 time the weight again gradually decreases until during the last 

 day of pupation when it is uniform. The abrupt drop at the end 

 of the curve represents the casting off^ of the pupa cases. 



Sarcophaga sarraceniae (Fig. 3): This curve is based on the 

 growth of a series weighed every six hours during the feeding 

 period (see Table III, column 2). The curve shows several 

 interesting features. In the first place the increase in weight is 

 really prodigious, beginning with an average weight of 0.2 mg. 

 (10 larvae equals 2 mg.) and increasing to an average of 90.2 mg. 

 in seventy-one hours, an average hourly increase of 1.270 mg. or 

 an increase of 45,100 per cent of the original weight. This aver- 

 age for larvae of this species is not high since many individuals 

 which were weighed for another purpose ranged from 150 to 200 

 mg. (75,000 to 100,000 per cent) and over and were probably de- 

 veloped from larvae weighing no more than the above at extrusion. 

 This species did not show a decrease in weight at the beginning 

 of the feeding period as Lucilia. 



Another remarkable feature is the large and rapid drop in 

 weight after migration. This loss is just about one-half of the 

 average original weight of the migrating larvae. The pupal 

 period is characterized by a small but comparatively regular loss 

 in weight. 



f Percentage increment curves (Figs. 4 and 5): Since applying 

 the percentage increment method used by Minot ('91) the writer 



