INDIRECT BENEFITS DERIVED FROM INSECTS. 163 
beginning to quit their slough, others prepared to fly, and others already on 
the wing; and every where under the water they were to be seen in 
a greater or less degree of forwardness. The storm coming on, he was 
obliged to quit the amusing scene; but when the rain ceased to fall, he 
returned to it. As soon as the cloth with which he had ordered the tub 
to be covered was removed, the number of flies appeared to be greatly 
augmented, and kept continually increasing ; many flew away, but more 
were drowned. Those already transformed, and continually transforming, 
would have been sufficient of themselves to have matle the tub seem full ; 
but their number was soon very much enlarged by others attracted by the 
light. To prevent their being drowned, he caused the tub to be again 
covered with the cloth; and over it he held the light, which was soon 
concealed by a layer of these flies, that might have been taken by handfuls 
from the candlestick. 
But the scene round the tub was nothing to be compared with the 
wonderful spectacle exhibited on the banks of the river. The excla- 
mations of his gardener drew the illustrious naturalist thither; and such 
a sizht he had never witnessed, and could scarcely find words to describe. 
“The myriads of Ephemera,” says he, “which filled the air over the 
current of the river, and over the bank on which I stood, are neither to 
be expressed nor conceived. When the snow falls with the largest flakes, 
and with the least interval between them, the air is not so full of them as 
that which surrounded us was of Ephemere. Scarcely had I remained in 
one place a few minutes, when the step on which I stood was quite con- 
cealed with a layer of them from two to four inches in depth. Near the 
lowest step a surface of water of five or six feet dimensions every way was 
entirely and thickly covered by them ; and what the current carried off 
was continually replaced. Many times I was obliged to abandon my 
station, not being able to bear the shower of Ephemera, which, falling 
with an obliquity less constant than that of an ordinary shower, struck 
continually, and in a manner extremely uncomfortable, every part of my 
face — eyes, mouth, and nostrils were filled with them.’ "To hold the 
flambeau on this occasion was no pleasant office. The person who filled 
it had his clothes covered in a few moments with these flies, which came 
from all parts to overwhelm him. Before ten o’clock this interesting 
spectacle Pad vanished. It was renewed for some nights afterwards, but 
the flies were never in such prodigious numbers. The fishermen allow 
only three successive days for the great fall of the manna; but a few flies 
appear both before and after, their number increasing in one case, in the 
other diminishing. Whatever be the temperature of the atmosphere, 
whether it be cold or hot, these flies invariably appear at the same hour in 
the evening, that is, between a quarter and half-past eight ; towards nine 
they begin to fill the air; in the following half-hour they are in the 
steatest numbers ; and at ten there are scarcely any to be seen. So that 
in less than two hours this infinite host of flies emerge from their parent 
stream, fill the air, perform their appointed work, and vanish. A very 
large proportion of them falls into the river, where the fish have their 
stand festival and the fishermen a good harvest.! 
Under this head I may observe how much the patient angler is indebted 
to insects for some of his choicest baits, for the best opportunities of 
1 Reaum, vi. 479—487. 
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