290 



A YEAR IN SCIENCE 



Permission of U. S. Dept. of Agricul- 

 ture. 



Fig. 139. The tussock moth is a 

 common insect injurious to shade trees. 

 F, adult female ; E, adult male ; D, 

 larva; K, females laying eggs on bark 

 of tree ; /, pupae in cocoons. 



Permission of U. S. Dept. of Agriculture. 



Fig. 140. The potato beetle is one of the 



best known of the garden pests. 



us each year of about 

 $500,000,000 worth of 

 crops, forest trees, 

 and lumber. There 

 are thousands of dif- 

 ferent kinds of these 

 pests. Some devour 

 foliage, others attack 

 fruits and seeds, and 

 still others bore into 

 the wood of the tree 

 on which they live. 

 In combating with 

 insects the farmer 

 is assisted and 

 directed by the 

 Bureau of Entom- 

 ology of the United 

 States Department 

 of Agriculture and 

 by various state 

 experimental sta- 

 tions. The most 

 effective means of 

 control thus far 

 found is by poison- 

 ous sprays. By 

 this method both 

 the adult and the 



