276  NATURE’S MEANS OF LIMITING THE NUMBERS OF INSECTS. 
enumeration, for we should never finish if we mentioned all, the A 
rapacious birds, such as the screech owl, the buzzard, the kite, — 
more accustomed to live on flesh, are sometimes forced to content 
tend and complete, it follows from the great number of birds that — ; 
there is daily an immense destruction of insects. It is not by 
thousands only, but by hundreds of thousands, by millions, a+ 
cording to the area embraced, that we should count in fine weather G 
` and from one sunny day to another, the number of victims: The — 
imagination shrinks at the idea of the total to which we should : — 
reach at the end of a.year.” hte ie 
Mr. Perris then says, the main question is, How many of the in- — | 
sects thus eaten are injurious? We will quote our author’s conclu a 
sions, though we think that in desiring to show that the protection — 
and culture of birds are not the only way to prevent the attacks 7 
of injurious insects, as many of his countrymen think, he 1s 
little disposed to underrate on his side their importance, which is l 
felt in this country especially, in dealing with injurious caterpi- 
lars, such as the tent caterpillar,canker worm and the bud worm 
(Penthina oculana) of the apple and'thé pear, which would other: 
wise annihilate our apple and pear crop, as they almost threaten 
to do now. Remarks M. Perris :— 
1, “ Birds are only united in troops more or less considerable : 
the times of migration of autumn and spring, that is to say when 
most insects are infinitely less numerous than during the summi 
The rest of the time, they live ordinarily in couples apart 
themselves, quite rare in cultivated grounds, while the ince 
vade en masse the trees they wish to attack, the crops of Wie 
they are the enemies. : ve 
2. “ Birds destroy insects enormously, but these insects até à 
not serve particularly our interests; they even injure us, MANJ 
them devouring our fruits as well as seeds either planted here 
soil, or harvested, and especially in suppressing the carnlv 
parasitic kinds which render us great service. ok 
8. “The insects of which we have the most to complain are i 
large enough to defy the birds, or (and these are the most 1" pee 
able) too small to draw their attention; some of them tasi? | 
badly to excite their appetite; many are nocturnal and 
day, with that instinct of self-preservation which is’ as M 
veloped i i 
in them as in the larger animals ; or, living inactive, 
