HONOR, Mich. (AP) — A small insect that can kill hemlock trees by feeding on their sap has been detected at the Sleeping Bear Dunes National Lakeshore in northwestern Michigan.

Earlier this month, surveyors found round, white ovisacs characteristic of the hemlock woolly adelgid on one tree in the Platte River Campground in Honor, Michigan’s Department of Agriculture and Rural Development said.

The popular campground is in northern Benzie County, southwest of Traverse City.

The insects’ feeding weakens needles, shoots and branches of the trees. Over time, tree growth slows and trees take on a grayish-green appearance.

Without treatment, infested trees die within four to 10 years, state officials said.

Michigan has been combating hemlock woolly adelgid since 2006 and has current infestations in Allegan, Ottawa, Muskegon, Oceana and Mason counties. The insect was detected in October in Ludington State Park, about 70 miles south of Sleeping Bear Dunes.

Hemlock woolly adelgid likely arrived in Michigan on infested nursery stock from northeastern states, officials said.

The tiny insects don’t move far on their own, but they can be blown by wind or carried by birds or mammals that come into contact with an infested branch. Cars, boats or recreational vehicles parked beneath infested trees may also be able to transport the insects to new locations.