220 The Natural History of Se I borne 



districts in the south seas, near Guiaquil,* are desolated, it 

 seems, by the infinite swarms of venomous mosquitoes, which 

 fill the air, and render those coasts insupportable. It would 

 be worth inquiring whether any species of hirundines is found 

 in those regions. Whoever 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 Irippoboscce hinmdinis, 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 tick- 

 ling 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 pupcv 

 of these insects ; but for other particulars, too long for this 

 place, we refer the reader to " L'Histoire d'Insectes " of that 

 admirable entomologist. Tom. iv., pi. ii. 



* See " Ulloa's Travels." 



