REMEDIES FOR THE CANKER-WORM 



BV CLARENCE M. WEED 



During the last two or three years an increasing injury has 

 been done to many orchards in New Hampshire by the canker- 

 worm. This injury is so serious, and might be prevented with 

 such comparative ease, that this bulletin is issued to give the 

 orchardists of the state the latest information concerning 

 methods of combating the pest. 



The remedial measures to be used against any insect can 

 best be understood when we know in some detail the life- 

 history of that insect. This is particularly true of the canker- 

 worm, because one of the practical methods of fighting it is 

 dependent upon a peculiar fact in its life-history. 



In briefest summary the story of a canker-worm's life is 

 this : In early spring, about the time the leaves begin to push 

 out from the buds, it hatches from an egg previously laid upon 

 the bark of a twig or branch by a small, wingless moth. The 

 little canker-worm immediately begins to feed upon the green 

 and succulent tissues of the young leaves, a process which it 

 continues from day to day for about a week. It then is too 

 large for the skin with which it was born, and so it moults 

 or sheds its skin, crawling out of the old one, clothed in a 

 new one that had been formed beneath the other. It soon 

 begins feeding again, eating more and more of the green tis- 

 sues of the leaf as it grows larger. About a week later this 

 moulting process is again repeated, after which the caterpil- 

 lars continue feeding as before. In the course of five or six 

 weeks of such growth the canker-worms become full grown 

 so far as this caterpillar state is concerned. 



When thus full grown the canker-worms are green or 

 brown, varying much in color, more or less striped with longi- 



