June 12, 2008

LANSING, MI - The Michigan Department of Agriculture (MDA) concluded its intensive survey to detect Hemlock Woolly Adelgid (HWA), a serious exotic and invasive forest pest in the northern Lower Peninsula. MDA inspected more than 20,000 hemlock trees growing on 4,300 acres in the Petoskey area looking for signs of HWA.

“Despite regulatory and inspection efforts, the sheer volume of plants and plant products commercially shipped into our state inevitably results in the movement of plant pests,” says Don Koivisto, MDA director. “Strong early detection programs and aggressive responses are required to insure the viability of Michigan’s forest and agricultural ecosystems.”

The survey was part of a joint effort by MDA, the Michigan Department of Natural Resources, and Michigan State University, after HWA was confirmed at five locations in Harbor Springs in 2006 and 2007 (four in 2006, one in 2007). Removal and destruction of infested hemlock, multiple insecticide treatments of adjacent trees, and additional detection efforts preceded the surveys completed this month.

Native to eastern Asia, the HWA was discovered in Virginia in 1951, and has since spread to Georgia and Maine, decimating hemlock stands across much of the eastern United States. The Michigan infestations originated from hemlock nursery stock grown in West Virginia and planted for residential landscaping in Harbor Springs.

“Hemlock Woolly Adelgid is a serious threat to our valuable forest resource. More than 100 million hemlock trees are present in Michigan’s forests, providing valuable habitat for diverse populations of animals such as birds, deer, and fish,” said Bob Patterson, MDA Plant Pest Specialist. “Continued surveys for this pest are essential to prevent its permanent establishment in the state.”

Adelgids are small, aphid-like insects that use their long, siphoning mouthparts to extract sap from conifer trees. In North America, the HWA survives only on hemlock. It gets its “woolly” name from the white, cottony mass that covers its body and protects its eggs.

MDA has established quarantine against HWA to prevent the movement of infested hemlock nursery stock and products into Michigan from infested areas. For more information about the HWA quarantine, please visit MDA’s Web site at www.michigan.gov/mda.