116 NATURAL HISTORY OF SELBORNE. 



several corrections and additions, it is hoped that the republication of 

 them will not give offence ; especially as these sheets would be very 

 imperfect without them, and as they will be new to many readers who had 

 no opportunity of seeing them when they made their first appearance.] 



" The hirundines are a most inoffensive, harmless, entertaining, social, 

 and useful tribe of birds ; they touch no fruit in our gardens ; delight, 

 all except one species, in attaching themselves to our houses ; amuse us 

 with their migrations, songs, and marvellous agility; and clear our 

 outlets from the annoyances of gnats and other troublesome insects. 

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

 by the infinite swarms of venemous 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 sun-beams 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 ; t 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 Mppoboscw 

 hirundinis, with narrow subulated 

 wings, abounding in every nest ; 

 and are hatched by the warmth of 

 the bird's own body during incuba- 

 tion, 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 



1. HIPPOBOSCA HmroiHNia. *****?* like a crab. It creeps 



2. NIEMI. under the tails, and about the groins, 



of horses, which, at their first coming 



out of tb,e north, are rendered half frantic by the tickling sensation ; 

 while our own breed little regards them. 



" The curious Keaumur 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 pupce 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." 



t Or ^irmi, now fully described in the ' ' Jlouographia Anoplurorum Britanniae, ' 

 by Henry Denny ; who has also in readiness for publication materials sufficient 

 for a volume upon the parasites of exotic species, as well as on those which infect 

 many of the foreign mammalia. This volume would be of great interest, .and only 

 requires sufficient encouragement to be brought out. 



