60 NEW YORK STATE MUSEUM 



ways by several writers. Professor Peck thought it was cut so as to permit 

 of the insect's retreat being kept moist, as it would be if it lay on the 

 ground amid leaves and snow. This can hardly be the reason since it 

 is well known that this species is easily reared from very dry limbs. INIr 

 Chittenden has suggested the following, which appears to us to be the 

 most reasonable explanation. He states that most of the larvae in hard 

 wood cut their way nearly out before the final transformations take place. 

 The small portion of the bark remaining is left to protect the insect from 

 birds and other enemies. There are some species that have well developed, 

 strong mandibles in the adult condition and these can make their way through 

 solid wood, as for example Monohammus. Many others, and among them 

 this species, are not thus favored and they would be utterly unable with 

 their weaker mouth parts to make their way through solid wood. These 

 exit channels are very frequently run at an angle to the axis of the wood, as. 

 is well known, and since this twig girdler works in such small limbs that this 

 method of escape would be impracticable, the cutting off of the limb and 

 plugging of the free end with borings seems to be the easiest and most 

 natural way of getting around the difficulty. Dr Fitch gives considerable 

 space to discussing the infallibility of this larva in cutting off the limbs but 

 such is hardly borne out by facts. Mr Chittenden states that this can 

 hardly be true and cites Dr Fitch who observed that at least i,:^ of the fallen 

 limbs contained no grub and an examination of these showed that the insect 

 must have perished at the time the limb was severed or before it had exca- 

 vated an)- burrow upward in its center. 



The life cycle of this species is probably completed under natural con- 

 ditions in one year, though when breeding in dry twigs the period may 

 be considerably extended. Dr Hamilton states that in some cases 3 and 

 probably 4 years are required to complete the life cycle, and the writer is 

 inclined to agree with Mr Chittenden in accounting for this extended 

 period by the retarding influence of undue drying which may easily obtain 

 in breeding cages. The writer has reared a number of the beetles and 

 failed to observe any such prolonged life cycle. 



