of life; a few tortoiseshells, and so on--even the white butterflies are
quite uncommon, the whites that used to drift along like snowflakes.
Where are they all? Did the snow kill them? Is there any connection
between the absence of insects and the absence of swallows? If so, how
did the swallows know beforehand, without coming, that there were no
insects for them? Yet the midsummer hum, the deep humming sound in the
atmosphere above, has been loud and persistent over the hayfields, so
that there must have been the usual myriads of the insects that cause
this sound. While I was thinking in this way a swallow alighted on the
turf, picked up a small white moth from among the short grass, and went
off with it. In gloomy overcast weather the swallows at the sea-side
frequently alight on the pebbles of the beach to pick up the insects
which will not rise and fly. Some beaches and sandbanks are much
frequented by insects, and black clouds of them sometimes come drifting
along, striking the face like small hail.

When swallows fly low, just skimming the ground, it is supposed to be a
sign of rain. During the frequent intervals of heavy, overcast weather
which have marked this summer, they might have been observed flying low
for a week together without a spot of rain falling. Chilly air drives
insects downwards, and, indeed, paralyses a great many of them
altogether. It is a fall of temperature, and not wet, that makes the
swallows chase their prey low down. Insects are not much afraid of rain
if it is warm and soft, so that in the midst of showers, if there is
sunshine too, you may see the swallows high in the atmosphere. It is when
they fly low, but just missing the grass, that their wonderful powers of
flight appear. In the air above there are no obstacles, and if you shoot
an arrow it travels to the end of its journey without let or hindrance;
there are no streets there to turn corners, no narrow lanes, no trees or
hedges. When the shallow comes down to the earth his path is no longer