No. 4.] BIRDS AND WOODLANDS. 305 



imagined. Two thousand of these insects were taken by the 

 birds from a small oak in front of his door within a few days. 

 Mr. Trouvelot, speaking of the birds which penetrated into 

 the enclosure in which he was raising the silkworms, quaintly 

 says: "The small ones could go through the meshes and 

 the larger ones through some holes in the old net. So I was 

 obliged to chase them all the day long, as Avhon pursuing 

 them on one side they would tiy to the other and quietly 

 feed, until I again reappeared." He expresses the belief that 

 in a state of nature 95 per cent of these insects are destroyed 

 by birds alone. 



But this is only one indication of the value of birds in this 

 respect. When settlers first began to plant orchards and 

 establish tree claims on the western prairies, there were few, 

 if any, arboreal birds there, except along the timbered river 

 bottoms. The settlers imported insect pests on young trees. 

 The enemies of tree insects being absent, because the country 

 was destitute of well-grown groves and orchards, the insects 

 increased and over-ran the seedling trees, the larger moths, 

 like the cecropia and the polyphemus, being the worst pests 

 of all, increasing rapidly, eating voraciously and making it 

 almost impossible to raise trees. Dr. Lawrence Bruner, in 

 a paper on insects injurious to tree claims, states that the 

 absence alone of so great a factor as these birds in keeping 

 down and ridding a country of its insect pests soon becomes 

 apparent in the great increase and consequent damage done 

 by these pests. He asserts, also, that as an enemy to tree 

 culture the cecropia has no equal in some portions of the 

 prairie country, and that its large caterpillars often defoliate 

 entire groves, — something unheard of here. Mr. W. C. 

 Colt, who has had ex{)crience in raising trees in Dakota, tells 

 me that the caterpillars of this and other large species were 

 terribly destructive there. As groves and orchards became 

 established, however, and arboreal birds spread over the 

 country, these caterpillars were reduced by them to a state 

 of comparative harmlessness. 



During the past two summers, 1898 and 1899, much injury 

 has been done to the woods in certain sections of New Eng- 

 land by the so-called forest tent caterpillar (^Olisiocanipa 

 disstria). Birds destroy great numbers of these pests, and, 



