SWALLOWS INSECTS. 181 



ever contemplates the myriads of insects that 

 sport in the sunbeams of a summer evening in this 

 country, will soon be convinced to what a degree 

 our atmosphere would be choked with them was 

 it not for the friendly interposition of the swallow 

 tribe. 



Many species of birds have their peculiar lice : 

 but the hirundines alone seem to be annoyed with 

 dipterous insects, which infest every species, and 

 are so large, in proportion to themselves, that they 

 must be extremely irksome and injurious to them. 

 These are the hippoboscte himndines, with narrow 

 subulated wings, abounding in every nest ; and are 

 hatched by the warmth of the bird's own body 

 during incubation, and crawl about under its 

 feathers. 



A species of them is familiar to horsemen in the 

 south of England, under the name of forest-fly, 

 and, to some, of side-fly, from its running sideways 

 like a crab. It creeps under the tails and about 

 the groins of horses, which, at their first coming 

 out of the north, are rendered half frantic by the 

 tickling sensation ; while our own breed little 

 regards them. 



The curious Reaumur discovered the large eggs, 

 or rather pupce, of these flies, as big as the flies 

 themselves, which he hatched in his own bosom. 

 Any person that will take the trouble to examine 

 the old nests of either species of swallows may find 

 in them the black shining cases or skins of the 

 pup& of these insects ; but for other particulars, too 

 long for this place, we refer the reader to 1'His- 

 toire d'Insectes of that admirable entomologist. 

 Tom.iv.pl. 11. 



