LIX.] 



OF SELBORNE. 



165 



Cue thing is remarkable that, after some years, the old holes 

 are forsaken and new ones bored ; perhaps because the old habi- 

 tations grow foul and fetid from long use, or because they may 

 fo abound with fleas as to become untenantable. This species 

 of swallow moreover is strangely annoyed with fleas : and we 

 have seen fleas, bed-fleas (Pulex irritans), swarming at the 

 mouths of these holes, like bees on the stools of their hives. 



The following circumstance should by no means be omitted 

 that these birds do not make use of their caverns by way of 

 hybernacula, as might be expected ; since banks so perforated 

 have been dug out with care in the winter, when nothing was 

 found but empty nests. 



The sand-martin arrives much about the same time with the 

 swallow, and lays, as she does, from four to six white eggs. But 

 as this species is cryptogame, carrying on the business of nidifi- 

 cation, incubation, and the support of its young in the dark, it 

 would not be so easy to ascertain the time of breeding, were it 

 not for the coming forth of the broods, which appear much 

 about the time, or rather somewhat earlier than those of the 

 swallow. The nestlings are supported in common like those of 

 their congeners, with gnats and other small insects ; and some- 

 times they are fed with libdlulcc (dragon-flies) almost as long as 

 themselves. In the last week in June we have seen a row of 

 these sitting on a rail near a great pool as perchers ; and so 

 young and helpless, as easily to be taken by hand : but whether 

 the dams ever feed them on the wing, as swallows and house- 

 martins do, we have never yet been able to determine : nor do 

 we know whether they pursue and attack birds of prey. 



When they happen to breed near hedges and inclosures, they 

 are frequently dispossessed of their breeding holes by the 

 house-sparrow, which is on the same account a fell adversary 

 to house-martins. 



These hirundines are no songsters, but rather mute, making 

 only a little harsh noise when a person approaches their nests. 

 They seem not to be of a sociable turn, never with us congre- 

 gating with their congeners in the autumn. Undoubtedly they 

 breed a second time, like the house-martin and swallow, and 

 withdraw about Michaelmas. 



