KAPLAN, La. (AP) — Josh Courville has harvested crawfish his whole life, but these days, he’s finding a less welcome catch in some of the fields he manages in southern Louisiana.Snails. Big ones.For every crawfish Courville dumps out of a trap, three or four snails clang onto the boat’s metal sorting table. About the size of a baseball when fully grown, apple snails stubbornly survive all kinds of weather in fields, pipes and drainage ditches and can lay thousands of bubblegum-colored eggs every month.AdvertisementAdvertisement“It’s very disheartening,” Courville said. “The most discouraging part, actually, is not having much control over it.”Apple snails are just one example of how invasive species can quickly become a nightmare for farmers.In Louisiana, where rice and crawfish are often grown together in the same fields, there’s now a second threat: tiny insects called delphacids that can deal catastrophic damage to rice plants. Much about these snails and insects is still a mystery, and researchers are trying to learn more about what’s fueling their spread, from farming methods and pesticides to global shipping and extreme weather.Experts aren’t sure what role climate change may play, but they say a warming world generally makes it easier for pests to spread to other parts of the country if they gain a foothold in the temperate South.AdvertisementAdvertisement“We are going to have more bugs that are happier to live here if it stays warmer here longer,” said Hannah Burrack, professor and chair of the entomology department at Michigan State University.It’s an urgent problem because …
