136 THe BLOwFuiEs or NortH AMERICA 
p. 19) to vary in Texas from about 7 days during midsummer 
to about 54 days during winter. Travis, Knipling, and Brody 
(1940) conducted detailed experiments upon the depth in the 
soil at which americana larvae pupated. They found that in 
nature all puparia of this species are found within the top 14% 
inches of the soil, the majority within 14 inch of the surface. 
They also noted that larvae tended to pupate in clumps of vege- 
tation if such were present, that pupation was slightly deeper 
Fie. VIII. Callitroga americana myiasis wound in steer initiated by 
acid-branding operation. Note the deep pocket-type wounds. Savannah, 
Ga., May 12, 1935. 
where the vegetation was more sparse, that larvae migrated 
farther where there was no vegetation than when the vegetation 
was dense, and that pupation occurred somewhat deeper in moist 
soil in the laboratory than in the field. Sixty-six percent of the 
puparia were found in a vertical position, 30 percent at an 
angle between vertical and horizontal i Aa and 4 perce in 
a horizontal position. 
Adult. The adult usually emerges from the pupae between 
the hours of 4 to 7 a.m. The preoviposition period is from 5 to 
