38 



such actions." " Instinct," Todd says in his Cyclopaedia of Anatomy and Physiology, " is 

 a special internal impulse urging animals to the performance of certain actions which are 

 useful to them or to their kind, but the uses of which they do not themselves perceive, 

 and their performance of which is a necessary consequence of their being placed in certain 

 circumstances." 



If such definitions are accepted, how are they to be reconciled with the marvellous 

 statement as given by Dr. Fitch 1 That the larva should prune the branch to prevent 

 the flow of sap would be a necessary consequence of its being placed in certain circum- 

 stances, but to do so that the branch may fall to the ground presents a course of reasoning 

 that relates to a condition foreign to the then existing environment. The habits of this 

 beetle from the period of egg-hatching, as given by Dr. Fitch, displaying as it did to him 

 extraordinary intelligence, impress me as presenting the most natural instinctive 

 qualities. The ova, he says, is deposited on a small green twig, the soft, pulpy tissues of 

 which nourish the infant larva, which, when increased in size and strength, attacks the 

 hard wood of the branch, transversely, in a circular direction, consuming it all, leaving 

 the branch supported only by the bark. From these premises, without pursuing the 

 subject further, it is evident that the infant larva requires sap-wood for its sustenance, 

 which it derives from the twig, but so soon as its strength permits, it seeks for dead-wood 

 by attacking the branch, which is found more and more free from sap as the work of 

 severance progresses. The aim therefore from the start is to obtain the dead-wood, and 

 when the branch is eaten through the larva continues its feeding in forming a tunnel 

 through that portion of the branch which is cut off from the supply of sap. 



The instinct of insects is wonderful enough, and more accurate perhaps than a mental 

 process, but while we justly ascribe to them all the attributes pertaining to their natural 

 gift, we are not warranted in imputing to them an intelligence only to be arrived at 

 through a course of reason. 



THE OAK PRUNER : ELAPHIDION VILLOSUM, Fabr. 



BY JOHN HAMILTON, M. L\, ALLEGHENY, PA. 



The account of this insect given by the early fathers of (Economic Entomology is so 

 charming that it seems almost profane to disturb a history accepted by most of their 

 credulous offspring with unquestioning faith. Its wonderful habits and supra-rational 

 instincts have been stock in trade ever since, and, like the fiction of the fly walking on 

 glass by a sucker arrangement of its feet, is likely to hold its place in paste and scissor 

 literature for all time to come. 



Divested of all romance and imagination, and descending to facts, the observations 

 of Professor Peck, Fitch and Harris may be reduced to this. In the month of July the 

 parent lays the eggs on the limbs, or in the axil of a leaf near the end of the twigs of 

 that year's growth of various species of oak, and perhaps other trees. After hatching, 

 the young larva (in the latter case) penetrates to the pith and devours it downwards till 

 the woody base is reached, and so onward to the centre of the main limb ; here it eats 

 away a considerable portion of the inside of the limb, and then plugging the end of the 

 burrow, which it excavates towards the distal end, eventually falls to the ground with the 

 limb, which being weakened, is broken off by the high autumnal winds. They exist here 

 either as larvse or pupae till spring, and emerge in June as perfect beetles. Time, one 

 year, though not so stated in words. 



The account given in detail below is so different from the above, that were the 

 identity of the individuals not established by actual comparison and by recognized 

 authority, it might well be asserted I had given an account of some other Elaphidion. 



April, 1883, I procured a barrel of hickory limbs from a tree girdled early in 1882 ; 

 the limbs were from one-half to one inch in diameter. Very few things developed from 

 them that season ; but the next (1884) quite a number of species came forth — Clytanthus 



