Hello Daniel

This treatment information is from MSU Extension bulletin— —https://www.canr.msu.edu/resources/how_to_treat_hemlock_trees_for_hemlock_woolly_adelgid

Landscape trees can be effectively protected from HWA with systemic insecticides containing imidacloprid or dinotefuran. These products are typically applied as a soil drench or basal trunk spray, or via a professional trunk injection in the fall or early winter. Many products are available to certified pesticide applicators, and a few products can be purchased and applied by homeowners. Dinotefuran moves into and through hemlock trees relatively quickly, making it an ideal choice for rapid control of HWA, especially on large, old trees. Dinotefuran, however, must be reapplied every 1-2 years. Imidacloprid moves slowly through hemlock trees but will persist for at least 4 years.

The product examples in the bulletin may not be available anymore, but there are others. Check the label of products for the active ingredient and choose one that the label indicates controls HWA. Read the directions so you know how much product to buy— application rates depend on tree size. Please, always follow all directions and cautions on the product label.

If you would like to hire a certified arborist to treat your trees, find them by zip code search here: http://www.treesaregood.org

You may report your HWA so that Michigan can keep its maps up to date.

https://www.michigan.gov/invasives/id-report/insects/hemlock-woolly-adelgid