28 
Mr. F. H. Chittenden has estimated, from experiments re¬ 
cently conducted by him in Washiugton, that in the warmest 
weather the lile cycle is about five weeks. In my experimental 
work during midsummer, under the most favorable conditions, 
in California and Illiuois, I have been unable to get a full grown 
larva in less than five weeks from the time it emerged from the egg. 
The number of annual broods of ihis insect depends largely 
upon the geographical location and upon the condition of the 
mill. In California, where the climate is even, the amount of 
damage done and inconvenience caused varies but little with the 
time of year. In the Eastern States, however, the insect is most 
troublesome during the summer m mths; although in exceptionally 
warm mills it is very annoying even in midwinter. I have shown 
by a series of carefully planned experiments that there are from 
five to six annual broods in California, and probably the same 
number in some of the Southern States and iu Eastern States where 
the mills are well heated during the winter months. In most 
cases, however, in the East, four broods seem to be the average, 
appearing most abundantly from April to December. Brood after 
brood have appeared successively in my cages for the past two 
years. 
From a long series of experiments, I have selected five repre¬ 
senting the life cycle of this insect, the eggs being deposited in 
April, August, and October. The results are given in the follow¬ 
ing table: 
