CH. II] SWALLOWS KILLED BY PARASITES. 165 
were crowded with young Martins—as many per- 
haps as four or five in each—sunning their barred 
white breasts, and waiting to be fed: the telegraph 
wires formed perches, of which advantage was 
taken by scores of others more advanced in 
growth, and of old ones reposing after their exer- 
tions; while the air was filled with others em- 
ployed in catering for their families. All of a 
sudden the young ones retreated into their holes; 
the wires were deserted, and only a few remained 
visible describing distant circles. I thought that 
a Hawk must have made his appearance, but it 
turned out that the alarm had been caused by two 
men walking over the heath above, and approach- 
ing the holes. The young ones in the holes had, 
no doubt, felt the jar caused by their tread, and 
those on the wing, who saw them, had probably 
given warning, by note, to the others perched on 
the wires, who could not have seen, nor, I should 
think, heard their approach. 
Two well-authenticated instances have come 
within my knowledge in which Swallows have, 
while in the act of flying, fallen to the ground co- 
vered with and partly devoured by insects. Of the 
fact there seemed to be no doubt, but the descrip- 
tion of the insects furnished me by my informants 
