14 THE MAGAZINE OF HORTICULTURE. 



their retreats, and derive from them almost their whole sub- 

 sistence. 



Fifthly, there are many families of insects that come abroad 

 only during the night. Many of these, on account of their 

 size and numbers, are very destructive ; and they are like- 

 wise the progenitors of some of the most mischievous of the 

 borers or wood-worms. Nature, as a check to their excessive 

 increase, has created certain tribes of nocturnal birds, which, 

 like the swallows, catch their food chiefly on the wing. 

 Among these are the birds of the whippoorwill tribe, includ- 

 ing in this country only two species. The little barn owl 

 also labors for the same beneficent end. 



I shall treat of the different services of these respective 

 tribes of birds in the order in which I have arranged them. 

 I have named the swallows as the natural checks to the in- 

 crease of the swarming insects. They feed on these alone, 

 taking all their food while on the wing. They are more nu- 

 merous than any other single genus of birds : they are found 

 in every country and climate, and after the first of May, in 

 this country, may be seen flying, from the earliest to the 

 latest hour of day-light, in quest of their aerial prey. The 

 atmosphere may be considered their proper element, for so 

 small are their feet and legs that they are scarcely able to 

 walk. They seldom tire on the wing, flying with as much 

 ease as a fish swims the sea. They not only feed on the 

 wing, but they even drink and bathe, by suddenly immersing 

 themselves in the water, without discontinuing their flight. 



There can be no doubt that were it not for the services of 

 swallows, the atmosphere would be rendered unfit for respira- 

 tion, and that the multitudes of these swarming insects might 

 generate a universal pestilence. The quantity of flies con- 

 sumed by them proves them to be remarkably voracious for 

 their size. A quantity of flies has been found in the crop of 

 a single bird equal in bulk to a small hen's egg. Their inde- 

 fatigable exertions in pursuit of their prey are unequalled by 

 those of any other bird, and their continuance on the wing 

 would seem impossible, did we not consider the lightness of 

 their bodies, and the large size of their wings, enabling them 

 to sustain themselves in the air almost without eff"ort. 



