Half-eaten hotdogs and other food litter aren't just gross, it also feeds pests like pigeons, rats, and flies, which harbor and spread human pathogens. And cleaning up is pricey: In 2008, the US spent about 11.5 billion on cleaning up after sloppy eaters, according to a study by the anti-litter group Keep America Beautiful. The same study found that food accounted for up to 26 percent of all the waste on American streets.

A new study suggests that if we could figure out how to manage them, ants could be like tiny clean up crews, and help us starve out populations of larger pests that can carry disease.

A covered and uncovered food pile. Each pile contained hot dogs, cookies, and potato chips. Youngsteadt et al

Researchers placed food dishes at median strips throughout Manhattan to see how much food insects could put down. Half of the trays had open sides any scavenger could access, but the rest were surrounded with mesh that only insects could crawl through. The insects held their own: Nearly as much food disappeared from the trays with mesh as from the trays without it.

The researchers estimate that insects in the median strip of a single block would eat the equivalent of 300-500 hot dogs over the course of a year. The little scavengers were also surprisingly resilient. "In the middle of our work, Hurricane Sandy happened and some of our study sites were under water for several hours or days," said Elsa Youngsteadt of North Carolina State University, and an author of the study, published today in Global Change Biology. However, the flooding that shut down much of lower Manhattan for a week had no effect on how much food the critters ate.

One species, the pavement ant, turned out to be the dominant scavenger. Pavement ants are an invasive species, originally from Europe, found in nearly all US cities. They like hotter, drier places (like median strips), are voracious eaters, and are hugely territorial. "They have big colonies, and can quickly call in a lot of workers when they find a food source," Youngsteadt said.

Youngsteadt and colleagues also repeated the experiment in parks. Because parks have more species than inhospitable median strips, the researchers hypothesized that more food would be consumed, as different scavengers would be attracted to different types of food. Not so, however. Big scavengers appeared to consume roughly the same amount of food waste in parks as in median strips, but insects consumed two to three times less.

Overall, Youngsteadt says the new study shows that the pavement ants are eating enough garbage to be considered competitors to other, less desirable scavengers. "A lot of people grumble when an ant shows up in their kitchen, but they want a rat even less," she said. With more research, she says, it might be possible to create urban wildlife management plans that encourage the type of scavengers we'd prefer.