399 



cure but few, and those during but a short period, and they are 

 obliged therefore to subsist principally upon the great destroyers 

 of leaves, canker-worms, and some other kinds of caterpillars and 

 bugs. If each robin, old and young, requires for its support an 

 amount of these equal to the weight consumed by his bird, it is 

 easy to see what a prodigious havoc a few hundreds of them must 

 make upon the insects of an orchard or a park. Is it not then to 

 our advantage, he asks, to purchase the service of the robins at the 

 price of a few cherries ? There has lately been some improve- 

 ment in i^reserving our birds, and with a little more protection, 

 he thinks that such an increase of them might be obtained as 

 would save us from all the labor required for the appliances of 

 tar, oil, zinc plates, and all other methods by which we seek, with 

 very imperfect success, to destroy our mischievous insects. 



The thanks of the Society were voted to Prof. Tread- 

 well for his communication. 



An animated discussion took place on the use of 

 birds, and especially of the robin, in destroying insects. 



Prof Parsons did not believe that the robin ever devours the 

 canker-worm, and his observation had not convinced him that 

 any bird does ; he was also of opinion that man destroys few 

 birds in comparison with cats and their other natural enemies ; 

 he alluded to an opinion of the late Dr. Harris, of Cambridge, 

 that insects perish from the attacks of tlieir own parasites, the lat- 

 ter gi'owing the more numerous whenever the necessity arises. 



Mr. Wetherel observed, that the robin eats caterpillars, but 

 whether canker-worms or not he did not know ; insects injurious 

 to fruit and to grasses have also been found in its crop ; he be- 

 lieved the squirrels, introduced on Boston Common and other 

 public and private enclosures, are the worst foes of the insec- 

 tivorous birds by destroying their eggs ; he considered also the 

 crow one of the farmers' best friends, though he does pull up a 

 few roots of the young corn, by his destruction of grubs and 

 insects injurious to vegetation. 



Dr. White remarked, that he had seen birds of the genus Vireo 

 eagerly devouring canker-worms. 



