There are, by some estimates, more than 40 million acres of green lawns in the U.S., making turf grass the largest irrigated crop in the country. A new book suggests that landowners repurpose some of their landscaping for another purpose: creating a “Homegrown National Park,” a connected network of more natural gardens that could help stave off the insect apocalypse and the collapse of broader ecosystems.

“We have data showing we’re deep into the sixth great extinction,” says Douglas Tallamy, a professor of entomology and wildlife ecology at the University of Delaware and the author of the new book, called Nature’s Best Hope: A New Approach to Conservation That Starts in Your Yard. “Things are disappearing on a regular basis. And those are the things that run the ecosystems that support us.”

A recent U.S. report on biodiversity found one million plant and animal species at risk of extinction, and insects are at particular risk. Another paper in 2019 found that insects face a rate of extinction eight times faster than mammals and birds, and the mass of insects is dropping so quickly that they could disappear within a century; because insects are essential for nature to function, their loss could trigger a “catastrophic collapse of nature’s ecosytems,” the researchers wrote. The species at imminent risk include those that are well-known, like varieties of bumblebees and dragonflies, and those that are obscure, like the Ohlone tiger beetle.

Industrial agriculture, and pesticides, bear much of the blame. But habitat loss is another part of the problem. By repurposing parts of lawns as native habitat, and ending the use of chemicals on lawns themselves, insects would have a better chance of survival. So would birds and other animals that rely on insects for food, and plants that rely on insects for pollination.

“If we’re going to have any birds, any life around us—and we need to, because those are the things that run our ecosystems—you have to have the food webs that support them,” Tallamy says. “Lawn is terrible at that. It’s not making any food for wildlife.”

A typical American lawn made of non-native grass, modeled originally on landscaping that wealthy European landowners used on their estates to signal that they were rich enough to avoid growing food on vast swaths of land. In American suburbs, there’s an expectation, often codified in local law that specifies how grass should be maintained, creating an unbroken sea of green across front yards. Lawns require huge amounts of water—by an EPA estimate, nine billion gallons a day—more than native plants adapted to local regions. They also don’t absorb carbon as well as other plants. “The cool season European grasses that we have as our primary turf grasses have very short root systems,” Tallamy says. “Compared to any other plant, they’re the worst at carbon sequestration.”

He calculates that if homeowners converted just half their land to native plantings, it would collectively create an area larger than all national parks in the lower 48 states combined; it would also create better connections between existing national parks and preserves so that animals would have a better chance at survival. Even the smallest animals, like insects, struggle when their populations become fragmented, limited to the range of a preserved area.