Ecological and Experimental Study of Sarcophagidce 5 1 



larvae to find a suitable place of entrance. Eighty-two living 

 larvae were taken from one female. 



Compsomyia macellaria, the screw-worm fly, deposits very 

 minute living young, but is careless about placing them on the fish. 

 This habit of bringing forth living young seems to be exceptional 

 in this region for the species. From thousands of eggs promiscu- 

 ously collected, not a single screw-worm fly was reared; all were 

 Lucilia caesar, and all observations in the field resulted in seeing 

 living young extruded. Prof. J. S. Hine, of Ohio State University, 

 reports that he has seen Compsomyia deposit eggs and that he has 

 also reared them from eggs at Cedar Point. 



Larval Habits 



The young larvae, when hatched or extruded, at once eat into 

 the softer parts, attacking the viscera and later consuming the 

 muscular portions. The fish is eaten clean to skin and bone, the 

 skin remaining as a mere shell; this, too, would be eaten to the 

 scales were the entire surface sufficiently moist. This is evident 

 because the portion of skin nearest the earth, where it is moist, 

 is invariably eaten away, leaving a hole in the under side, which 

 incidentally allows a concealed means of escape during migration. 



Migration depends wholly on the food supply. If the fish is 

 large enough and the number of larvae is not too great, migration 

 takes place in from two and a half to three days, during which 

 time the larvae have reached their full growth. If the number of 

 larvae is large in proportion to the fish, migration takes place earlier. 

 This phase of the subject is treated below under the head of "Over 

 and Underfeeding." 



On leaving the remains, the larvae immediately burrow into the 

 sand below or close by the fish. The great majority burrow just 

 beneath, going down two to six inches into the sand and remaining 

 there temporarily. This migration may take place any time during 

 the day or night, though the tactics vary for these periods. Bur- 

 rowing temporarily just beneath the fish carcass during the day 

 not only affords protection from the intense heat of the sun but 

 also from birds. On cloudy days when migration sometimes takes 

 place away from the fish, the sandpipers, in numbers, feed on the 



