THE OAK PRUNER. 5 



Although this species normally completes it transformations in 

 amputated or fallen limbs, it occasionally breeds in limbs that have 

 not been severed. It does not always cut off the twigs in which it 

 Hyes, and the larva sometimes reverses the order of proceedings and 

 directs its burrow 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. John Hamilton," however, has stated that a longer period 

 is required, three years being the usual time, and in individual cases 

 four or more years being consumed. The writer is strongly inclined 

 to beMeve such exceptionally long periods, even three years, to be the 

 result of undue dryness caused by unnatural indoor conditions. 



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, who wrote of this species in 1819,'' 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 migjxt 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 Fitch concurred. 

 Mr. Frederick Clarkson, however, took issue with Fitch, beheving 

 that the main object of the larva is to obtain deadwood and to 

 prevent the flow 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 hmbs 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 



a Hamilton, John.— Canadian Entomologist, vol. 19, pp. 141-145, 1887. 

 6 Peck, William D.— Mass. Agr. Repos. and Journ., vol. 5, pp. 307-313, Jan., 1819. 

 (Treated as Stenocoris putator Peck. Not seen.) 

 [Cir. 130] 



