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severed. It does not alway cut off the twigs in which it lives, and the 

 larva sometimes reverses the order of proceedings and directs its bur- 

 row toward the distal end of the branch, which it cuts off at the end of 

 its burrow and remains in the branch attached to the tree. 



From the earlier accounts of Fitch and others it would be inferred 

 that the insect requires a single year only for the completion of its life 

 cycle. Dr. Hamilton, however, states that a longer period is required, 

 three years being the usual time, in individual cases four or more years 

 being consumed. The writer is strongly inclined to believe such excep- 

 tionally long periods, even three years, to be the result of undue dry- 

 ness caused by indoor breeding. 



WHY THE LARVA AMPUTATES A LIMB. 



The purpose of the larva in cutting away the wood furnishes an 

 interesting topic for speculation. The object attained is its ultimate 

 fall to the ground. 



Peck thought that the limb, if permitted to remain attached to the 

 tree, would become too dry and that a certain degree of moisture was 

 required for the development of the insect, and that the limb was 

 accordingly partially severed that it might eventually fall, and that 

 then, lying on the ground amid the autumn leaves and beneath the 

 winter's snow, the requisite degree of moisture was insured. In this 

 belief Dr. Fitch concurred. Mr. Clarkson, however, takes issue with 

 Fitch and believes that the main object of the larva is to obtain dead 

 wood and to prevent the now of sap. Here we have two contrary 

 views expressed, one that the object is to obtain moisture, the other to 

 prevent it. 



Such an excess of moisture, as is obtained on the ground under the 

 melting snow and the pools of water that collect in winter under the 

 infested trees, could hardly be a necessity in the life history of any 

 terrestrial animal. The ease with which these insects may be reared 

 from dry twigs indoors is conclusive proof to the contrary. Why they 

 should require more moisture than fifty or a hundred others that could 

 be named that have similar food habits and do not breed exclusively 

 in fallen limbs, it would be difficult to explain. Again, that the small 

 flow of sap of oak or hickory could seriously interfere with develop- 

 ment would seem unreasonable when we consider that these insects are 

 able to survive the immersion to which they are sometimes subjected 

 for days together during thaws and rainy spells in the winter. 



Another explanation of the limb's amputation occurs to the writer. 

 Those who have reared beetles from hard wood cannot have failed to 

 observe that the larva before transforming cuts through the wood 

 until it reaches the bark, which is left untouched and serves to protect 

 the insect from marauding birds or other enemies. When the beetle 

 develops it has only to gnaw its way through this thin layer of bark to 

 effect its exit. There are undoubtedly some wood borers which are 



