52 Thirty-seventh Annual Eeport oe the 



such portions of their food-plant as they traverse, and a final acceptance 

 of that most agreeable to them. By a process like this the Orgyia larva 

 may have made the discovery, that just at the commencement of the 

 new growth, as the result of the seasonal conditions above mentioned, 

 there was concentrated in the tender bark nutriment far more ac- 

 ceptable to it than that offered in the leaves, upon which alone it had 

 hitherto been accustomed to feed. As the bark hardened with the 

 advancing season it would cease to be acceptable for food. 



The interesting query here arises, suggested by the frequency with 

 which new habits in insects are brought to the notice of the en- 

 tomologist: will the taste for bark newly acquired by the Orgyias of 

 the last year, be conveyed, through heredity, to their descendants, to 

 be continued through future years and displayed to an extent meas- 

 ured by the degree of tenderness of the bark at the period of their 

 appearance ? 



The falling of the twigs, in the condition as above given, was first 

 observed about the middle of June. Upon my return to Albany, 

 after a fortnight's absence, on the 27th of July, twigs were still fall- 

 ing, but among them* was a large proportion in which a new feature 

 was presented. The breaking, instead of being at the base of the 

 girdling, just above the commencement of the new growth, was, in 

 these, at the preceding node, covering the growth of the former year. 

 As a rule, the twigs showed a greater diameter at their decorticated 

 portion, compared with those of the earlier fall. The greater strength 

 thus given them permitted them to remain upon the tree until the 

 death of the preceding internode, which soon followed the arrest of 

 the circulation — its starvation ensuing, it being unprovided with 

 leaves through which a circulation could still be maintained. When 

 dead a slight motion of the branch, or even the weight of the termi- 

 nal leaves would be sufficient to disconnect it at its lower and weaker 

 node. 



About the 1st of August the twigs ceased to fall. I have not made 

 examination to see whether any of those upon which the above attack 

 was made still remain upon the trees. 



Nothing of the kind was observed as occurring upon the other 

 principal food-plants of the Orgyia, viz. : the horse-chestnut and the 

 maple, nor would it be expected in association with growth and struc- 

 ture so entirely different from that of the elm. 



The same phase of attack was noticed by me in Troy, N. Y. I 

 have seen no publication of its presence elsewhere, although the cater- 

 pillar was quite abundant in New York and other of our larger cities. 



The English Sparrow promoting Insect Injury. 



In connection with the incidental mention above of the almost an- 

 nual defoliation of so many of our more valuable shade-trees by the 

 Orgyia caterpillars, it may be of interest to state that there is every 

 reason to believe that we owe the commencement and regular returns 

 of this annoying form of insect depredation to the introduction into 

 our city, about the year 1868, of the English sparrow, Passer domesti- 

 cus, and its subsequent rapid increase and diffusion. The sparrow 

 does not feed upon the insect, but drives away the four species of birds 



