HORSE-FLIES AND WESTERN AGRICULTURE. 7 



nature. Water was added from time to time to approximate the 

 natural amount of moisture. For food, small snails and earthworms 

 were placed in the jars. The worms were usually cut into pieces 1 

 to 2 inches in length. 

 The snails were intro- 

 duced alive. Of the 

 two the snails were 

 of the most value as 

 food. The larva 

 would crawl into 

 the shell and devour 

 •the entire contents. 

 In making observa- 

 tions on the prog- 

 ress of the develop- 

 ment of the larva 

 the entire contents of 

 the jar was dumped 

 onto a white granite 

 platter, where the 

 search for the larva 

 could be carefully made. Often it was found completely concealed 

 within the shell of a snail. 



The small one-room building constructed for the laboratory was 

 widely open on each side and properly screened (fig. 0). This 

 afforded good circulation of air. 



At the beginning an attempt was made to duplicate soil tempera- 

 tures and to provide a more uniform temperature than that which 

 would result from leaving the jars exposed to the air. Galvanized- 

 iron pans 4 inches deep and large enough to contain 12 jars were 

 used. Water several inches deep was kept in the pans. This pro- 



s used for rearing horse-flies. 



Fig. G. — The Held Laboratory for horse-fly investigati 



cedure was soon abandoned because time and facilities were not 

 available to determine its value and because successful rearings 



could be made without it. 



