THE PEA APHIS WITH RELATIOX TO FORAGE CROPS. 45 
It will he observed that only one record of a winged female was 
noted, and this individual required a noticeably longer time to reach 
maturity than did the wingless forms observed at the same time. 
This has been our observation time and again, although no definite 
records were kept. 
AGE AT WHICH FEMALES BEGIN REPRODUCING. 
In 1912 the age at which females began giving birth to young varied 
from 6 to 35 days, with an average of 10.3 days, from 38 records 
covering the months from May 15 to December. (Table Y.) 
