Mark Twain,
Roughing It — Chapter XXXVIII
(1872)
“ These settle on the beach to eat the worms that wash ashore—and any time, you can see there a belt of flies an inch deep and six feet wide, and this belt extends clear around the lake—a belt of flies one hundred miles long. If you throw a stone among them, they swarm up so thick that they look dense, like a cloud. You can hold them under water as long as you please—they do not mind it—they are only proud of it. ”
