A tree-killing pest has found its way into Sleeping Bear Dunes National Lakeshore and its spread has affected state natural resource officials.

The threat comes from the woolly adelgide of the hemlock, which is described as an aphid and is native to East Asia. They form small white masses on the underside of the branches and go under the bark to feed on the sap.

“After a few years of feeding the hemlock tree, the hemlock wool adelgid will kill the hemlock,” said Robert Miller, an invasive species specialist with the Michigan Department of Agriculture and Rural Development.

Miller said the hemlocks help protect the dunes from erosion, act as a home and shelter for birds and deer, and keep the inland trout streams cool and clear.

“We need our hemlocks here in the state because they help hold our sand dunes in place near our lakeshore, keep our rivers cool and clean, and protect our wildlife habitats,” he said. “So you are an important resource.”

He said the hemlock’s woolen adelgid was already present in the lake areas of west Michigan and likely hitchhiked campers into the dunes.

Miller said, unchecked, the pests are a threat to 170 million hemlocks across the state – they grow anywhere from wild forests to suburban landscapes. He said naturalists were particularly concerned that humans would unwittingly bring the pest to the upper peninsula.