Two billion people can’t be wrong—at least, not about the nearly 2,000 species of insects that make for good eatin’ around the world. But nobody has to pitch you on the benefits of insectivory, right? Easier on the environment, full of weird nutrients, and whoa, check out that feed conversion ratio: It takes half as much food as you’d give to pigs and chickens and a twelfth as much as cattle to get the same amount of cricket protein on the far side of the abattoir. If Earth might have to feed 9 billion people in the coming decades, insects are what’s for dinner. Ask the United Nations.

But let’s slow down this Snowpiercer train a bit. Insects like crickets and beetles are, indeed, a very good source of protein and other nutrients. But the ones that humans already eat tend to be wild-caught and consumed in comparatively small numbers. That’s not the scaled-up future of insectivory that the UN foresaw in 2013. Factory farm facilities that can breed, raise, kill, and ship millions of critters require more food as input, output more waste, and raise thorny issues from entomology to ethics. “Actually, we don’t know that much,” says Åsa Berggren, an ecologist at the Swedish University of Agricultural Sciences in Uppsala who has been trying to sort out how sustainable an insect-based menu would be. “And people don’t know what we don’t know.”

That ignorance should bug you, because we humans have already steered our food system into a sustainability crisis. As any soy-swilling vegan will tell you at the drop of a hemp-knit hat, the global system of raising animal protein for people to eat has flaws. People use 77 percent of the world’s agricultural land to grow feed for meat animals, even though they represent just 17 percent of calories consumed. Livestock emit 14.5 percent of climate change-causing greenhouse gases; farmed hogs represent a possible reservoir of pandemic-causing influenza viruses; chicken farming fueled the development of antibiotic-resistant bacteria; and giant pools of hog waste threaten natural disaster every time a hurricane brushes the Carolinas.

But those aren’t problems with animal protein per se; they’re problems of scale and capitalism. And now the future of insects as food threatens to become every bit as industrial. Some European countries already have “mass-rearing facilities, enormous, like airplane hangar-sized,” Berggren says. But it doesn’t have to be a catastrophe. The newly buzzy insect biz is an opportunity. “If you start with totally new animals, we should be able to do it better. Knowing what we know now, what could we change if we started all over again, so we don’t continue to make it worse?”

Writing in the journal Trends in Ecology and Evolution, Berggren and her colleagues lay out a sort of anti-review article, a litany not of what’s known but of the unknowns that emerge when a swarm of new companies start mass-producing insects. According to one analysis, edible insects will be a $710 million global market in the next five years—multiple species, ground into flour or sold as bars and snacks. But growing up all those insects will mean more space for unintended consequences.

So, for example, today people use a huge amount of land on Earth to grow plants then fed to animals so people can eat the animals. Insects need less of that food to become more protein, and more of each insect (depending on the species) is actually edible—insects, having chitinous exoskeletons, make no bones about that. But that still means productive agricultural land has to be turned from feeding people to feeding critters. What you’d really like is to scroll through the thousands of edible insects and find species that grow fast, aren’t too finicky about living conditions, and most importantly are not picky eaters. Best case: insects that eat something people don’t, or can’t—solving a recycling problem while freeing up land to grow food for humans instead of human prey. And at the other end of the problem, it’d be great to figure out how much waste zillions of insects create, what’s in it, and how to use it.