32 



cumstances this stage is reduced to about five weeks. Mr. James 

 Fletcher writes that moths kept in a breeding cage in his study, 

 coutinued to emerge and lay eggs until December 15. He then 

 adds in a foot-note, that larvae from these eggs were full grown 

 March 21. This makes a period of ninety- five days, and wouH 

 seem to indicate that in Canada the development of the larva is 

 very much slower than in California, or in Illinois and New 

 York, during the winter months, as in no case have I observed 

 the larval period to last longer than forty- nine and a half days. 



When the larvae reach maturity they have the peculiar habit of 

 migrating to some isolated corner for pupation, and will then 

 leave their feeding quarters provided an outlet is afforded. It is 

 difficult to confine them in a breeding- cage at this period, and in 

 my cages many larvae have escaped by working their way out un- 

 derneath the stout rubber bands which held the muslin over the 

 cage. After maturity the larva will often crawl about for one or 

 two days, without taking any food, before finding a suitable place 

 for its quiescent stage. The cocoon, in which the chrysalid rests, 

 is made of fine silk, often intermingled with particles of flour or 

 meal. These cocoons are sometimes found in great masses in the 

 most remote parts of a mill. The adult moths emerge in about 

 two weeks, and deposit their eggs for succeeding generations. 



Mr. Sidney T. Klein, in a paper read before the Entomological 

 Society of London, refers to the peculiar migratory habits of the 

 flour moth as follows: | 



"Their migratory habits, when full-fed, were very extraordinary; 

 nothing seemed to keep them within bounds. I had a colony of 

 some thousands in my house, in order to make experiments how 

 to exterminate them; but I found that my breeding-cages, with 

 the finest meshed wire, were useless to restrain them. I then 

 placed them under a large glass shade on a polished surface with 

 no perceptible outlet; but it was no use; the corners and ceiliog 

 of my room were within a week studded with their cocoons, and 

 every day specimens of the larvae were discovered in different 

 parts of the house, from top to bottom; in fact, they increased 

 and wandered to such an alarming extent that I had to give up 

 keeping them." 



In the same paper, speaking of the creatures in the warehouse 

 where he made his observations, Mr. Klein says: 



"When full-fed the larvae made their way to the surface, and 

 could be seen in myriads crawling along the floor and up the 

 walls of the warehouse, till they reached the angle where the roof 

 met the walls. There they spun compact silken cocoons, in which 

 they turned to the pupa state." 



HISTOKY OF THE CALIFORNIA OUTBREAK. 



In March, 1892, the president of one the largest milling firms 

 on the Pacific coast invited me to visit one of his mills which, he 

 said, was literally overrun with worms and moths. I inspected 

 the mill the latter part of March, and procured a large number 



