244 HALF HOURS WITH INSECTS. [Packard. 



above the place where it is partially severed, until a high 

 wind occurs. If the limb is not hereby broken, as soon as 

 the weather becomes calm he very probably returns and 

 gnaws off an additional portion of the wood, repeating this 

 act again and again, it may be, until a wind comes which 

 accomplishes the desired result. And this serves to explain 

 to us why it is that the worm severs the limb at such an 

 early period of his life. For the formidable undertaking of 

 cutting asunder such an extent of hard woody substance, we 

 should expect he would await till he was almost grown and 

 had attained his full strength and vigor. But by entering 

 upon this task when he is but half grown he has ample 

 opportunity to watch the result, and to return and perfect 

 the work if he discovers that his first essay fails to accom- 

 plish the end he has in view. 



"Thus the first part of the life of this worm is passed in a 

 small twig branching off from the main limb. This is so 

 slender and delicate that on being mined as it is by the 

 worm and all its green outer end consumed, it dies and be- 

 comes so decayed and brittle that it is usually broken off 

 when the limb falls, whereby it has escaped the notice of 

 writers, hitherto. The remainder of his larval life is passed 

 in the main limb, first cutting off this limb sufficiently for it 

 to break with the force of the winds, and then excavating a 

 burrow upwards in the .centre of the limb, both before and 

 after it has fallen to the ground, feeding hereon until he has 

 grown to his full size." 



Fitch adds that "not only the limbs, but small j^oung 

 trees, at least of the white oak, are sometimes felled by 

 these insects ; in which cases the worm instead of cutting 

 the wood off transversely, severs it in a slanting or oblique 

 direction,, as though it were aAvare the winds would prostrate 

 a perpendicular shoot more readily by its being cut in this 

 manner." 



The larvo3 become fully grown in the autumn, and some 



20 



