392 



How Living Things Affect One Another unit vii 



Fig. 342 Damage to corn, done by the larvae 

 of the European corn borer. It docs even 

 greater da?iiage hi weaken'mg the stalks, (u. s. 



BUREAU OF entomology) 





Fig. 343 Caterpillars of the gypsy nioth moving 

 tip a tree. What stops their progress? How do 

 gypsy moth caterpillars harm trees? (u. s. de- 



PARTiMENT OF AGRICULTURE) * 



doing Exercises i and 2. Then let us see 

 how this information is being put to 

 practical use. 



How we fight the European corn borer. 

 The European corn borer, which has 

 been in our country for only about 

 twenty-five years, has spread through 

 many states. It causes much damage in 

 moist years, usually less damage in dry 

 years. The small moths are good fliers 

 and they spread rapidly. The moth lays 

 its eggs on the leaves of the corn or on 

 some of the commonest ^^'ecds. The 

 small larvae feed on the outside of the 

 plant for a few days and then enter the 

 ear (Figure 342) or the stalk within 

 which they spend the winter. It is un- 



usual for larvae to live through the win- 

 ter; in most insects it is the pupa which 

 winters over. These larvae spin cocoons 

 and soon after come out as adults. You 

 can see that one method of control might 

 be that of destroying the stalks after har- 

 vest but before the moths emerge in the 

 spring. This is only partially successful 

 because it has not been possible to de- 

 stroy all the cornstalks and the M^eeds 

 which may contain larvae. To find out 

 about the most harmful insects in your 

 neighborhood do Exercise 3. 



Catching the chinch bug and the gypsv 

 moth. The chinch bug is a tiny insect 

 with sucking mouth parts. It is less than 

 a quarter of an inch long, yet it multi- 



