(Caltech)Mark Twain, when he traveled to California’s Mono Lake almost 150 years ago, became enchanted by aquatic flies. Mono Lake is peculiar — its three times saltier than the ocean and nearly as basic as ammonia. (Other flies, even oil flies that lay eggs in the petroleum of the La Brea Tar Pits, could not escape the Mono Lake water, the authors found.) The Mono Lake flies, which are as long as a housefly and weigh about as much as two sesame seeds, must exert forces 18 times their body weight to dive underwater. But the Mono Lake flies are odd bugs.