246 INDIRECT BENEFITS DERIVED FROM INSECTS. 



company them in astonishing numbers, preying upon them in 

 their larva state. The common sparrow, though proscribed 

 as a most mischievous bird, destroys a vast number of insects. 

 Bradley has calculated that a single pair, having young to 

 maintain, will destroy 3360 caterpillars in a week.^ They 

 also prey upon butterflies and other winged insects. The 

 fly-catchers (^Muscicapa), and the warblers {Motacilld)^ which 

 include our sweetest songsters, are almost entirely siipported 

 by insects ; so that were it not for these despised creatures 

 we should be deprived of some of our greatest pleasures, and 

 half the interest and delight of our vernal walks would be 

 done away. Our groves would no longer be vocal ; our 

 little domestic favourites the red-breast and the wren would 

 desert us ; and the heavens would be depopulated. We 

 should lose too some of the most esteemed dainties of our 

 tables, one of which, the wheat-ear, is said to be attracted to 

 our downs by a particular insect.- Lastly, insects are the 

 sole food of swallows, which are always on the wing hawking 

 for them, and their flight is regulated by that of their prey. 

 When the atmosphere is dry and clear, and their small game 

 flies high, they seek the skies ; when moist, and the insects 

 are low or upon the ground, they descend, and just skim the 

 surface of the earth and waters ; and thus by their flight are 

 regarded as prognosticating fair or wet weather. I was one 

 summer much interested and amused by observing the tender 

 care and assiduity with which an old swallow supplied her 

 young with this kind of food. My attention was called to a 

 young brood that, having left their nest before they were 

 strong enough to take wing, were stationed on the lead which 

 covers a bow window in my house. The mother was per- 

 petually going and returning, putting an insect into the mouth 

 first of one then of the others in succession, all fluttering and 

 opening their mouths to receive her gift. She was scarcely 

 ever more than a minute away, and continued her excursions 

 as long as we had time to observe her. When the little ones 

 were satisfied, they put their head under their wing and went 

 to sleep. The number of insects caught by this tribe is in- 

 conceivable. But it is not in summer only that birds derive 



^ Reaum. ii. 408. 



2 Bingley, ii. 374. 



