288 INDIRECT BENEFITS DERIVED FROM INSECTS* 



clearing our gardens of caterpillars ; and tlie locust-eat- 

 ino- thrush is still more useful in the countries subject to 

 that dreadful pest : these birds never appear but with the 

 locusts, and then accompany them in astonishing num- 

 bers, preying upon them in their larva state. The com- 

 mon 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 3 . They also 

 prey upon butterflies and other winged insects. The fly- 

 catchers (Muscicapa) and the warblers (Motacilla), which 

 include our sweetest songsters, are almost entirely sup- 

 ported 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 depo- 

 pulated. — 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 5 . 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 prognosticatino- 

 fair or wet weather. I was last summer much interested 

 and amused by observing the tender care and assiduity 

 with which an old swallow supplied her young with this 

 :l Pueaum. ii. 408. b Bingley, ii. 374. 



