42 BULLETIN 420, U. S. DEPAETMENT OF AGRICULTURE. 



THE FIRST GENERATION. 



PIKST BllOOU Ul'' ECjIUS. 



Time of deposition. — The earliest deposition of eggs of the first 

 brood in rearing cages occurred April 16, and more or less regular 

 depositions continued for a period of 45 days. The time for the 

 occurrence of a maximum deposition, however, would appear to be 

 near the latter part of the period, and the irregularities previously 

 noticeable are probably due to weather conditions. 



Length of incubation. — A total of 212 observations made in this 

 connection show a range of variation in the length of the incubation 

 period of 4 to 11 days. A decrease in the length of the period was 

 somewhat noticeable as the season advanced, although exceptions 

 occur. An average period of 5.96 days is found for the entire 

 number. These results are shown in Table XXXV. 



