Eating meat is not something many would give up, but livestock put a lot of stress on the environment through greenhouse gas emissions. A group of Dutch scientists has asked whether insects might replace cattle as food.

Insects are already eaten in many parts of the world. Chapulines are served in southern Mexico, and silkworms are eaten in China. The Dutch scientists asked whether eating insects would be better for the environment.

So they kept and fed five different species of insect - mealworms, house crickets, migratory locusts, sun beetles and Argentinean cockroaches. The first three are edible as they are, while the latter two are not.

It turned out that insects produce a lot less greenhouse gas emissions per kilogram of body mass than cattle or even pigs do, especially carbon dioxide (CO2)  and methane (CH4).

For example, the locust, which is eaten as a delicacy over much of Africa, creates 110 grams of CO2 per day per kilo of body mass, and for every kilo gained emits an average of 734 grams. By contrast, beef cattle produce about 5.3-7.0 grams of CO2 per day per kilo of body mass, and 2,835 grams of CO2  for each kilo gained.

Pigs produce less CO2 per day - 21.6-29.6 grams - but make more when the weight gain is factored in, 734 grams of CO2
on average for each kilo.

For other greenhouse gases, notably methane, the cows do much worse. The locusts make almost no methane, while cows produce 0.239 to 0.283 grams of it per kilo per day. When weight gain is added, the pigs and cows look much worse - cows produce 114 grams of methane for every kilo of weight gain. The insects all produce less than 5 grams.

Dennis Oonincx, an anthropologist and animal scientist at Wageningen University in the Netherlands led the study. He says he is doing experiments now to measure how efficient the insects are. Insects, he said, should be more efficient users of feedstock because they are cold-blooded and grow quickly.

He acknowledges that getting people in the western world to adopt eating insects will be difficult. But in 80 percent of the world people see it as normal, he said.

Oonincx chose the species he did precisely because they are edible; the inedible ones were picked because they can be fed a wide variety of foods. The protein from those insects, he adds, can be extracted and put into a form that people in Europe and the U.S. would find more acceptable.

As for which ones he likes better, Oonincx says it's the house crickets - that get his vote. They are really very good, he said.