262 



AMERICAN FORESTRY 



forest. Insects and fungus will not as a 

 rule attack healthy, living trees, but, 

 when an invasion comes, there is not 

 enough recently killed timber to go 

 around, so that the insects concentrate 

 their attacks on a healthy tree and kill 

 it, with the object of attaining more 

 dead wood to operate in. And, with the 

 leaf -chewing varieties, the healthier the 

 tree is, the better victim it makes. 



Work of Timber Worms in Oak. 

 (a) oak timber worm; (d) sap timber worm. 



The part the birds play in keeping 

 down insects is enormous. For instance, 

 take the little green inch-worm which 

 we are wont to regard as a harmless 

 sort of creature, principally engaged in 

 measuring one for a new suit. To the 

 forester he is known by the sinister name 

 of canker worm, for he is the dread foe 

 of all tree life, absolutely voracious in 

 his attacks on all foliage, and denuding 

 a tree of every leaf it has got, if given 

 a chance. Yet one little vireo, nesting 

 nearby, will find and eat hundreds of 

 him in a single day. So will the harmless 

 little garter snake, who performs for 

 the bush life of the forest the same ser- 

 vice that the birds do for the tree life. 

 Nature has always kept down our 

 American canker worm species within 

 the limits of furnishing food for birds, 

 with a reasonable amount of leaves 

 supplied for the continuation of the can- 

 ker worm family, but, with the birds 

 gone, this restriction is removed and 

 there seems to be no limit to the canker 

 worm but the blue sky ! 



In the same way the 

 tribe have always kept 

 within reasonable bounds, 

 borers work just under the bark, making 

 big galleries through the cambium layer, 

 and cutting all the sap fibres, so that 



the sap flows to their precious offspring 

 instead of feeding the tree, and by the 

 time they have girdled a tree com- 

 pletely there is nothing for it but death 

 to the latter — usually two seasons of 

 borers will suffice to kill a perfectly 

 healthy tree that has taken fifty years 

 to reach its present stage of maturity. 

 The woodpeckers, nuthatches, creepers 

 etal. used to go over every tree carefully, 

 listening for the borers at work and 

 tapping the bark for hollow spots, and 

 when they left a tree every borer on it 

 had been found and eaten, to say noth- 

 ing of a few million cocoons and dor- 

 mant insects imder the crevices in the 

 bark. Nowadays, with one woodpecker 

 to a hundred acres of forest, man has 

 to do the principal fighting, and his 

 only remedy is to cut down the tree or 

 else make a woodpecker of himself 

 and go over the infected tree with an 

 oil can and a hatchet, squirting kerosene 

 oil into the borer galleries under the 

 bark. One remedy is worse than the 

 disease, except that it may save the 

 remaining trees, and the other is pretty 

 expensive, but worth trying in the case 

 of a fine, large tree, which used to send 

 down a bushel of hickory nuts every 

 season. 



Do not get the idea from the above 



woodpecker 

 the borers 

 All the sap 



Work of Pine Borers. 



(a) roundheaded borer, (c) flatheaded borer, 



larvae and adult beetle. 



that all our forests are necessarily going 

 to the bow-wows; far from it. Unless 

 you are located near large cities or 

 along heavily travelled railroads, the bulk 

 of your forest will be healthy if properly 

 managed. In the forest of Interlaken, 

 where the writer lives, we have about 

 three hundred acres of woodland, mostly 

 white oaks, red maples, sweet and sour 

 gums, chestnut oaks and some pine. 



