40 



provided in the beetle state with mandibles sufficiently powerful to 

 enable them to penetrate hard wood (Monohammus, fur example), but 

 the majority, among them Elaphidion, are not thus favored, and would 

 be utterly unable with their weaker boring organs to escape, and would 

 perish in their burrows had they not, while larvae, excavated the neces- 

 sary channel for their exit. These exit channels usually run at an 

 angle to the axis of the wood. Xow, in the case of our Elaphidion, 

 which usually lives in a slender limb which it bores longitudinally, 

 there is no room to place a branching, transverse channel; accordingly 

 the larva severs the twig and when it becomes a beetle it cuts its way 

 through the plug of castings. 



As to the larva apparently varying its operations to suit the different 

 sizes of limbs, the average infested twig is of about the thickness of 

 one's finger, and it is probable that the larva commences proceedings 

 late in the season with the approach of cold weather when it is about 

 full grown and ready for hibernation. To cut oft' the limb is a labor of 

 some magnitude for so small a creature and may require several days 

 for completion. It has a limited amount of energy, being now toward 

 the end of its active existence as a borer, and the cooler weather serves 

 to repress this energy, which is sufficient for cutting away all the wood 

 in a small twig, but is inadequate for a larger one. The wood of a large 

 branch is harder, and the insect ceases work, perhaps from exhaustion 

 or from cold, or because its instinct impels it to cut a certain amount, 

 and when that is accomplished to cease, its work being ended. At the 

 close of his narrative Dr. Fitch says, in spite of a previous assertion 

 that the insect never miscalculates, that — 



in at least three-fourths of the fallen limbs no worm is to he found; and an exam- 

 ination of them shows that the insect perished at the time the limb was severed 

 and before it had excavated any burrow upward in its center, no perforation being- 

 present except that leading into the lateral twig. It is probable that in many 

 instances the limb broke when the insect was in the act of gnawing it asunder, 

 either from its own weight or from a wind arising whilst the work was in progress. 



As might be inferred from the manner of life of this insect, it enjoys 

 as nearly perfect exemption from predaceous or parasitic attack as 

 falls to the lot of any wood borer. Fitch, however, has stated that 

 some of our insect-eating birds destroy the larva?, and the writer has 

 reared the parasite Bracon eurygaster Brulle from twigs inhabited by 

 the species. 



REMEDIES. 



In case this species becomes injuriously abundant, it may be readily 

 controlled by gathering the infested twigs during the winter and burn- 

 ing them before the following spring. 



The following summary of the known food and other habits of other 

 species of Elaphidion is appended: 



