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six (lavs not less than one hundred ami twenty oak leaves, Weighing 

 three-fourths of a pound, drinking in tin; mean time not less than one- 

 hall' ounce of water, the weight of the food eaten being cighty-si\ thou- 

 sand times the weight of the' worm on the first day. During this time 

 it has increased in weight four thousand one hundred and forty times. 

 The destructiveness of the species if allowed to increase may be im- 

 agined. 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 when pursuing 

 them on one side they would Hy to the other and quietly feed, until I 

 again reappeared." He expresses the belief that in a state of nature 

 ninety-five 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, 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-van 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 Brunei', 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 experience in raising trees in Dakota, tells me that 

 the caterpillars of this and other large species were terribly destructive 

 there. As groves ami orchards became established, however, and ar- 

 boreal 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 England by the so-called 

 forest tent caterpillar (Clisiocampa district). Birds destroy great 

 numbers of these pests, ami were birds more numerous there would 

 probably be no great outbreaks such as have occurred in recent years. 

 Dr. E. P. Felt, State entomologist of New York, says that one of the 

 most fruitful methods of keeping this pest in check through its natural 

 enemies will probably be found in encouraging and protecting the 

 native birds known to feed upon it.* 



As showing the large numbers of these caterpillars eaten by birds a 

 few notes trom Mr. Moshcr's observations will be of interest. A black- 

 billed cuckoo was seen to eat 'Mi forest tent caterpillars within five 

 minutes Red-eyed yireos (probably a pair) took 92 forest tent cater- 

 pillars from a tree within an hour. They were also eating span worms 

 and other larva' and plant lice. A male Baltimore oriole went into a 

 tree infested by these caterpillars, where he stayed four minutes, killing 

 IS caterpillars in that time : coming a little later he staved seven minutes 

 and took 2(\ caterpillars. A pair of blue jays came to the tree twenty- 

 four times during three hours, taking 2 or 3 caterpillars at each visit. 



All through the summer the trees are guarded by the birds. While 

 the white grubs of the .May beetle are stiil in the ground, ere they can 

 emerge to irvi\ on the foliage, the robins, crows, thrushes and blackbirds 



• Insects injurious to maple trees, 4th annual report, Commissioners Fisheries, 

 Game and Forest?. 



