10 



Texas Agricultural Experiment Station 



shell and its final emergence from the egg is made through a ragged 

 hole in the top. After the larva is out of the shell it appears white 

 and clear. 



INCUBATION period 



The period of incubation varies greatly with the brood and in the 

 cooler portions of the year this period is irregular within the brood. 

 The low temperature at which the vitality of the eggs is destroyed has 

 not been determined. 



In table 2 the eggs were from moths placed in an unheated room 

 and during this period the temperature averaged 65° P. 



Table 2. — Duration of egg stage, spring I9I2. 



The average period of incubation of this brood was 31.8 days. 



Table 3. — Duration of egg stage, fal'. 1912. 



These eggs were kept in the laboratory and the temperature averaged 

 about 95° F. The average period of incubation of this brood was 7.1 

 days. 



Table 4. — Duration of egg stage, winter 1912. 



These eggs were kept in the laboratory with artificial heat which 



