Dig in. Mealworms (Tenebrio molitor) grow faster and pollute less than cows or pigs, making them a potentially greener source of protein.

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To Fight Global Warming, Eat Bugs

Forget eating local or eating organic, the new way to dine green may be eating gross. Meat consumption presents a big environmental problem: Cows and pigs are good sources of protein, but they're also big sources of the heat-trapping gases carbon dioxide and methane, which they belch and, um, emit in other ways. One way to reduce such emissions while maintaining a nutritious diet may be to get people to eat more cricket burgers and mealworm patties. According to a new study, many insect species gain weight faster and spew out less greenhouse gases as they grow than do their beefier counterparts. The tricky part is getting them to look good on a menu.

A lot of work goes into transforming corn seed into a steak dinner. Irrigating fields, hauling feed to a feedlot, and running a farmer's truck all directly or indirectly produce greenhouse gases that cause climate change. So do cattle as they grow, releasing copious amounts of them through, for example, their droppings, or "cowpies," which give off methane as anaerobic bacteria digest the nutrients within. All told, livestock account for nearly one-fifth of humanity's greenhouse gas load, according to the Food and Agriculture Organization of the United Nations. But unlike warm-blooded, or endothermic, livestock, bugs don't spend much energy to keep themselves warm, so many scientists assume that pound for pound, they produce less greenhouse gas, too.

Dennis Oonincx, an entomologist at Wageningen University in the Netherlands, and colleagues wanted some hard data to back up that idea. They tested the output of three greenhouse gases—carbon dioxide, methane, and nitrous oxide—from five species of insects, including mealworms (Tenebrio molitor) and house crickets (Acheta domesticus). All five insect species were less wasteful than cattle and all but one performed better than pigs. Mealworms, for instance, churned out less than 1% as much greenhouse gas as cows and about 10% of a pig's smaller carbon hoof print. House crickets polluted even less, the researchers reported online 29 December in the journal PLoS ONE.

Oonincx says that based on these results, insects do seem to put more of their food into growing plump and less into polluting the atmosphere than do traditional livestock. "The species I've looked at so far suggest that insects could be a more environmentally friendly alternative," he says.

"It's a timely thing to do and imaginative, and I applaud them for that," says Peter Thorne, an environmental health scientist at the University of Iowa in Iowa City, who studies the public health impacts of traditional livestock. But it's hard to honestly compare cow and insect meat without a life-cycle analysis that looks at every component that goes into a burger, from land use to crop dusting, he says. Oonincx agrees and says that he's using these results as a jumping-off point for a more in-depth look at tiny ranching.

There's also the yuck factor to contend with. But, Oonincx says, insects have been an important part of the diet of many cultures for eons. As for recommendations, Oonincx says that mealworms are great in a quiche, but he prefers house crickets: "The structure and flavor are best."