118 NATURAL HISTORY 
wonderful, exceeding, if possible, the various evolu- 
tions and quick turns of the swallow genus. But 
the circumstance that pleased me most was, that I 
saw it distinctly more than once put out its short 
leg while on the wing, and, by a bend of the head, 
‘“When a person. approaches the haunts of fern-owls in an 
evening, they continue flying round the head of the obtruder, 
and, by striking their wings together above their backs, in the 
manner that pigeons called twisters are known to do, make a 
smart swap. Perhaps at that time they are jealous for their 
young, and their noise and gesture are intended by way of men- 
ace. Fern-owls have attachment to oaks, no doubt on account 
of food; for the next evening we saw one again several times 
among the boughs of the same tree, but it did not skim round 
its stem over the grass as on the evening before. In May these 
birds find the scarabeus melalontha on the oak, and the scarabeus 
solstitialis of midsummer. These peculiar birds can only be 
watched and observed for two hours in the twenty-four, and 
then in a dubious twilight, an hour after sunset, and an hour 
before sunrise.” 
‘‘On this day (July 14, 1789) a woman brought me two eggs 
of a fern-owl or eve-jar, which she found on the verge of the 
Hanger, to the left of the Hermitage, under a beechen shrub. 
This person, who lives just at the foot of the Hanger, seems 
well acquainted with these nocturnal swallows, and says she has 
often found their eggs near that place, and that they lay only 
twoatatimeonthebare ground. ‘The eggs were oblong, dusky, 
streaked somewhat in the manner of the plumage of the parent 
bird, and were equal insize ateach end. Fern-owls, like snipes, 
stone curlews, and some other birds, make no nest. Birds that 
build on the ground do not make much of nests.” 
“‘ Many of our oaks are naked of leaves, and even the half, in 
general, have been ravaged by the caterpillars of asmall phalena, 
which is of a pale yellow colour. These insects, though of a 
feeble race, yet, from their infinite number, are of wonderful ef- 
fect, being able to destroy the foliage of whole forests and dis- 
tricts. At this season they leave their animal, and issue forth 
in their fly state, swarming and covering the trees and hedges. 
In a field near Greatham, | saw a flight of swifts busied in catch- 
ing their prey near the ground, and found they were hunting 
after these phalene. ‘he aurelia of this moth is thin, and as 
black as jet, and lies wrapped up in a leaf of the tree, which is 
rolled round it, and secured at the ends by a web, to prevent the 
maggot from falling out.” 
