The southern coasts have long been bombarded by imported pests over the last century, and have taken many other beatings as well. From hurricanes, poisoning from oil spills. Now it is being eaten alive as invasive species decimates marshes.
Vast stands of marsh grass have been transformed into empty mudflats and open water, and scientists believe a plague of foreign insects is largely to blame. The tiny invaders have an insatiable hunger for Roseau Cane, a tall and hardy reed that binds together some of Louisiana’s most delicate stretches of coastline.
The insect, first observed in 2016, could not have chosen a worse target. As the Louisiana coast disappears at a rapid rate — about 10 square miles a year — roseau serves as a living, growing bulwark against land loss.
No one knows how or when the insect arrived, or what can stop it. It wasn’t until April that scientists could identify the pest: Nipponaclerda biwakoensis, commonly known as a scale. But by then it had spread over the lower Mississippi River Delta, consuming marshes that protect shipping channels, fishing and shrimping grounds, and hundreds of oil wells and pipelines.
The scale may reverse decades of coastal restoration and undercut major elements of Louisiana’s 50-year plan to slow land loss and limit damage from major storms.
“It very much looks like cancer on our marshes,” said Todd Baker, a biologist who works for the state. “It should be a concern not only for the citizens of Louisiana but the country at large.”
Walls of Roseau Cane sweep along every bayou and canal in the Delta National Wildlife Refuge, a 75-square-mile marshland that spreads like a fan into the Gulf of Mexico. About 10 feet high with densely packed stalks, the plant resembles bamboo, a distant cousin.
For James Harris, the manager of the refuge, dying roseau means a dying delta. “It’s what holds everything you see together,” he said from behind the wheel of a small boat. While many stalks stood tall, Mr. Harris said the scale was there, unseen, sucking the life out. He estimated that the insects were on 80 percent of the refuge. “Everywhere we’ve stopped, we’ve seen them.”
