INSECTS. 205 



1854, wheat to the value of fifteen millions of dollars. The 

 array worm of the north, which committed such ravages over a 

 large part of the country in 1861, is said to have done damage 

 that year to the extent of half a million of dollars in eastern 

 Massachusetts alone. 



These are all instances of injuries done by single species 

 of the more destructive insects. When we remember the 

 vast number of species of insects there are, and how many 

 species attack each one of our cultivated plants, we begin to 

 have some idea of the aggregate amount of the injury they 

 cause. At least a hundred species attack our cultivated ce- 

 reals and grasses, and probably as many more feed upon our 

 other field crops. At least seventy-five species attack the ap- 

 ple alone, and the shade and forest trees fare no better. Dr. 

 Packard calculates the total annual loss in our country from 

 noxious animals and the lower forms of plants, such as rust, 

 smut and mildew, as not far from five hundred million dol- 

 lars, and considers it a low estimate. I have not alluded in 

 these remarks to the injuries which insects and closely allied 

 animals do directly to man himself, and to domestic animals. 

 Prof. Verrill has given a full account of these in his lectures 

 on the " Parasites of Man and Domestic Animals," in the Re- 

 port of the Board for 1869, and has shown to what an extent 

 we suffer from them. 



There is another phase of this subject which I think should 

 be brought out more clearly than it usually is. We are too 

 apt to regard insects, if we thinlc of them at all, as wholly 

 injurious, I wish to correct this idea, which is too often pro- 

 mulgated. The lecturer last evening fell, unintentionally, 

 perhaps, into this common error, condemniiig as our enemies 

 almost the whole class of insects, and in turn exalting into 

 friends almost all the birds. Practically we can make no 

 such broad distinctions. Vast numbers, whole groups, in fact, 

 of insects are entirely beneficial, and many others more 

 friends than foes ; while the birds, likewise, must be divided 

 into friends and enemies. 



Of those insects which are directly beneficial to man, your 

 attention need not be called to the silk worms, to the honey- 



