Mark Twain described the odd diving flies (Ephydra hians) of Mono Lake, California in chapter XXXVIII of Roughing It – one of his finest books:
“Then there is a fly, which looks something like our house fly. 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. When you let them go, they pop up to the surface as dry as a patent office report, and walk off as unconcernedly as if they had been educated especially with a view to affording instructive entertainment to man in that particular way.”
A couple of Caltech scientists have now detailed exactly what’s going on with those superhydrophobic flies—whose Self-Contained Underwater Breathing Apparatus predates ours by a long stretch—with an overview article and video here. Links to their freely downloadable research paper and supplemental videos are at the end of that page.