180 NATURAL HISTORY 



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 bo 

 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 in- 

 sects, which infest every species, and are so large, in pro- 

 portion to themselves, that they must be extremely irksome 

 and injurious to them. These are the Hippoboscce, Tiirun- 

 dinis, 1 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. 2 



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 tho 

 pupce, of these insects : but for other particulars, too long 

 for this place, we refer the reader to " L'Histoire de? 

 Insectes" of that admirable entomologist, torn. iv. pi. 11. 



1 Craterina Jiinmdinis, OLFERS. 



2 In the New Forest, whence its name of forest fly, the Ilwpobosca 

 equina, LINN., abounds in such profusion that Mr. Samouelle states, in 

 his " Entomologist's Useful Compendium," that he has obtained from 

 the Hanks of one horse six handfuls, which consisted of upwards of a 

 hundred specimens. He adds, " Mr. Bentley informs me, from obser- 

 vations he made in the summer of 1818, while in Hampshire, that the 

 Hippoboscce are found in a considerably greater abundance on white 

 and light-coloured horses than on those of a black and dark colour ; 

 and this observation was confirmed by the stable-keepers in the vicinity 

 of the Forest." ED. 



