20 



ANIMAL BIOLOGY 



housekeeper, while usually based on the wrong inference that they 

 are actually engaged in eating her woolens, is, nevertheless, a 

 most valuable proceeding, because it checks, in so much, the multi- 

 plication of the species which is the sole duty of the adult insect. 



" There is no easy method of preventing the damage done by 

 clothes moths, and to maintain the integrity of woolens or other 

 materials which they are likely to attack demands constant vigi- 

 lance, with frequent inspection and treatment. In general, they are 



Uable to "affect injuriously 

 only articles which are put 

 away and left undisturbed 

 for some little time. . . . 

 Agitation, such as beating 

 and shaking, or brushing, 

 and exposure to air and 

 sunlight, are old remedies 

 and stiU among the best at 

 command. Various repel- 

 lants, such as tobacco, cam- 

 phor, naphthalene cones or balls, and cedar chips or sprigs, have 

 a certain value if the garments are not already stocked with eggs 

 or larvae. . . . Furs and such garments may be stored in boxes or 

 trunks which have been lined with the heavy tar paper used in 

 buildings. New papering should be given to such receptacles 

 every year or two." ' 



Fig. 15. — Life history of clothes moth. 

 (U. S. Dept. of Agriculture.) 



19. Silkworms. — One species of moth, the silkworm (Fig. 16), 

 is of great economic importance to man. The larva of this insect 

 feeds upon the leaves of the mulberry tree, and after reaching matm:- 

 ity it spins a cocoon, requiring about three days for its completion. 

 The silk is obtained by heating the cocoon in ovens to kill the pupa, 

 and then by reeling off the silk and spinning it into threads. " For 

 many hundreds of years the cultivation of the silkworm was con- 

 fined to Asiatic countries. It seems to have been an industry in 



1 Circular No. 36, Second Series, United States Department of 

 Agriculture. 



