The discovery of invasive hemlock woolly adelgid (HWA) in Leelanau Township, Leelanau County, Michigan, has raised concerns about the impact of this destructive pest on hemlock trees in the state. The Michigan Department of Agriculture and Rural Development (MDARD) recently confirmed the presence of HWA on trees on a private property, marking the ninth county in Michigan with active infestations. The extent of the infestation is currently being assessed through surveys of the surrounding area to determine the spread of the invasive species.
Molly Mott, MDARD’s Plant Health Section Manager, emphasized the importance of public awareness in combating invasive species like HWA. The Northwest Michigan Invasive Species Network played a crucial role in discovering this infestation, highlighting the need for vigilance and proactive measures to protect Michigan’s natural resources.
To help slow the spread of HWA, Leelanau County has been included in the statewide hemlock woolly adelgid quarantine. This quarantine restricts the movement of hemlock nursery stock and unprocessed hemlock material from quarantined areas, aiming to prevent further spread of the invasive pest to unaffected regions.
Hemlock woolly adelgids are small insects that feed on hemlock trees by extracting sap through their long, siphoning mouthparts. Their feeding can cause needles and buds to die, leading to canopy thinning, a grayish-green appearance, and slowed growth in infested trees. Without treatment, hemlock trees infested with HWA can die within four to ten years, posing a significant threat to Michigan’s estimated 170 million hemlock trees.
Deb McCullough, a Michigan State University Professor in the Departments of Entomology and Forestry, emphasized the ecological importance of hemlock trees, which provide essential wildlife habitat and contribute to stabilizing dunes. The loss of hemlock trees due to HWA infestations could have far-reaching consequences for Michigan’s ecosystems and biodiversity.
Identifying infested trees is crucial in managing HWA outbreaks. Look for round, white ovisacs near the base of hemlock needles on the undersides of branches, which indicate the presence of hemlock woolly adelgids. MDARD provides resources, including a short video guide, to help individuals identify and report suspected infestations accurately.
It’s essential to differentiate HWA from other pests that may resemble it to prevent misidentification. MDARD offers information on common look-alikes and guidance on identifying hemlock trees to assist in accurate reporting of HWA infestations. Taking precautions, such as avoiding parking under infested trees and cleaning gear before traveling, can help prevent the unintentional spread of HWA to new locations.
Reporting suspected HWA infestations in Leelanau County or other areas of Michigan is crucial for early detection and management efforts. Providing accurate location information and photos of infested branches can aid in confirming infestations without the need to collect sample branches or twigs, which could inadvertently spread HWA.
For more information on hemlock woolly adelgid and other invasive species in Michigan, visit Michigan.gov/Invasives to learn how you can help prevent the spread of these destructive pests. By staying informed and taking proactive measures, individuals can play a vital role in protecting Michigan’s forests and natural habitats from the threats posed by invasive species like HWA.
