18 BULLETIN 597, U. S. DEPARTMENT OF AGRICULTURE. 
developed and concealed within the rectum, but larve less than 
normal size, which were not exposed at the margin of the anus, did 
not produce adults. Only larve possessing the greenish color indi- 
cating exposure at the margin of the anus were used in experiments 
recorded in the tables. 
In Table IT, of 347 larvee collected, 319 pupated and produced 236 
adults, the pupa period varying from 21 to 68 days. The greater 
portion emerged during the shorter periods indicated in the table. 
FATE OF LARV4 DROPPING UNDER VARYING CONDITIONS. 
The variety of conditions under which larve are dropped naturally 
suggests the question of their ultimate fate. In an effort to deter- 
mine this point by experiments, the most striking phenomenon ob- 
served was the larval “ migration ” which precedes pupation. In ex- 
periments recorded in Table III, larve placed upon the surface of 
the soil or media penetrated to a slight depth for protection of the 
pup. With larve buried in loose soil, as would ordinarily occur 
when they are dropped by plow horses, they moved upward to near 
the surface for pupation. 
