THE INSECT CAMTAIGN I03 



weeks eating' by the species already nientionctl. Under 

 nearly all circumstances these leaf-eating- caterpi-llars 

 can be killed by the use of arsenical sprays. The es- 

 sential point in meeting these attacks is that the poison 

 must be given the insects before they reach maturity. 

 While the caterpillars are young, small and tender a 

 very trifling dose of arsenic will end their careers. If 

 they are three-fourths grown much larger doses are 

 required to kill them. Moreover after they have 

 reached maturity they are through eating. Their dam- 

 age is done. It is hardly worth while to poison them 

 then if we can. The absolute necessity of taking 

 these caterpillars in the first stages is often overlooked 

 by the men who use the spray remedy. 



Experience has shown that even in the severest at- 

 tacks of forest tent caterpillar the arsenical sprays will 

 protect orchards provided the work is promptly and 

 vigorously done, and provided other conditions of 

 orchard management are satisfactory. Some very 

 striking examples of this sort have come under the 

 writer's personaJ attention. 



Perhaps a special word should be said regarding the 

 fall web worm, which is one of the leaf-eating insects 

 most frequently seen in the northeastern states. This 

 insect appears almost every autumn, and on account 

 of its conspicuous webs in the apple trees, makes a 

 comparatively great showing. The fruit grower is apt 

 to be unduly alarmed because these worm nests are so 

 conspicuous. It should be remembered, however, that 

 the insects may be much less numerous and voracious 

 than those which make much less show earlier in the 

 year. An even more important fact is that at the time 

 the fall web worm appears the apple tree has prac- 

 tically completed its growth for the season. The leaves 



