498 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



moth. The larvae spin little silken tubes which protect them 

 while they are feeding in the flour or waste about the mill. 

 When full grown they wander about in search of a suitable 

 place to pupate, spinning a web wherever they go. It is this 

 habit that renders them most injurious, for the infested flour 

 and many parts of the mill become filled with the webs. This 

 necessitates frequent and expensive stoppings of work in the 

 infested mills. Great cleanliness about the mill is necessary. 

 When the insect becomes troublesome the mill should be 

 closed tightly and fumigated with hydrocyanic acid gas under 

 the direction of some experienced person. If the temperature 

 throughout the mill can be raised to about 120 F. and main- 

 tained there for a day, all moths, pupae, larvae and eggs will 

 be killed. 



COTTON 



The Boll-weevil (Anthonomus grand is). There are several 

 important enemies of the cotton plants, but during the last few 

 years the boll-weevil has become so important as to over- 

 shadow almost all the others. Indeed, one of these insects, 



FIG. 235. Boll-weevil, Anthonomus grandis. (Much enlarged.) 



the cotton-worm, which was formerly looked upon as one of 

 the worst enemies, is now regarded with some favor by many 

 planters because it sometimes aids in controlling the weevil by 

 stripping the late foliage from the plants and thus depriving 

 the weevil of its food. 



This small, brownish snout beetle is commonly known as the 

 Mexican cotton boll-weevil because, like several other insect 

 pests of the south, it came into the United States from Mexico. 



