See that bushy-tailed rodent chattering in the tree outside your house? It could be preparing to take down the electric grid.

Last year around Nashville, Tennessee, more power outages--2,257--were caused by squirrels and other creatures sharpening their teeth than by bad weather. This spring, a squirrel knocked out power for 23,000 people in California's Marin County, and last year one took out the water system in Tampa, Florida. Saboteur squirrels have turned out the lights at a sewage treatment plant, an airport, a hospital, a university, even a baseball game.

Animals monkey-wrench by chewing, touching wires together, or tripping switches. They almost always die in the process. But there are plenty of replacements. This spring, a raccoon snuffed out the lights for 5,700 households in Opelousas, Louisiana. In Holton, Kansas, snakes in a substation knocked out power citywide twice in five days.

"Wild animals are anywhere and everywhere and you can't predict that," Holton city manager Bret Bauer told the Topeka Capital-Journal. Sometimes they threaten catastrophe: In March, a rogue rat shorted out the cooling system at Japan's crippled Fukushima Daiichi nuclear power plant.

The greatest havoc, however, is wrought by crazy ants, who have colonized electrical appliances across the Southeast, shorting out burglar alarms, computers, and televisions. When their wriggling bodies bridge the circuit and they electrocute themselves, they send out a pheromone, calling in reinforcements. In a Waco, Texas, apartment complex, crazy ants took out 90 of the building's 150 air-conditioning units. 

They're not doing it on purpose, of course. But if animals were trying to destroy civilization, this is how they'd go about it.