the birds try to. Swallows and other insect-loving birds have a glorious
feast when the May flies come out. For a season they live in the midst
of more delicacies than they can possibly use.

Fish like the May fly larvæ, too, which is probably the reason the larvæ
have learned to live in the mud, out of reach.

Fishermen dig up the larvæ for bait, so you see the May flies have a
hard time to get safely through the world.

But in spite of difficulties a great many of them live, and some summer
day out they come trooping.

They spring all at once from the surface of the water as by magic,
hundreds and thousands, yes, millions of them. They fill the air, they
cover everything.

The great naturalist Swammerdam, who was the first to make a thorough
study of the May flies, thus tells us how they appeared in France one
year:--

"I then saw a sight beyond all expectation. The ephemeræ filled the air
like the snowflakes in a dense snowstorm.

"The steps were covered to a depth of two, three, or even four inches. A
tract of water five or six feet across was completely hidden, and as the
floating insects slowly drifted away, others took their places. Several
times I was obliged to retreat to the top of the stairs from the
annoyance caused by the ephemeræ, which dashed in my face, and got into
my eyes, mouth, and nose."