NATURAL HISTORY OF SELBORNE. 173 
latebre being left unfinished arise from their meeting in those places 
with strata too harsh, hard, and solid for their purpose, which they 
relinquish, and go to a fresh spot that works more freely? Ormay 
they not in other places fall in with a soil as much too loose and 
mouldering, liable to flounder, and threatening to overwhelm them 
and their labours ? 
One thing is remarkable—that, after some years, the old holes are 
forsaken and new ones bored ; perhaps because the old habitations 
grow foul and fetid from long use, or because they may so abound 
with fleas as to become untenantable, This species of swallow 
moreover is strangely annoyed with fleas ; and we have seen fleas, 
bed-fleas (Julex zrritans), 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 nidification, 
incubation, and the support ofits 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 sup- 
ported in common like those of their congeners, with gnats and 
other small insects; and sometimes they are fed with /dellule 
(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 enclosures, they are 
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 congregating with 
their congeners in the autumn. Undoubtedly they breed a second 
time, like the house-martin a swallow, and withdraw about 
Michaelmas. 
