Hello,

Protecting your boxwoods

If you are in or around the quarantine zone, you can use a preventative pesticide spray to protect your boxwoods or if you have a positive identification of box tree moths and need to treat them. We recommend in late July and early September, an application of bifenthrin (several ready-to-use products available at the garden center) or any pyrethroid insecticide for homeowner use can be used to control all life stages. Pyrethroid insecticides are those where the active ingredient ends in thrin, for example, cyfluthrin, permethrin, resmethrin, cypermethrin, lambda-cyhalothrin and sumithrin. Before using any pesticide, be sure to read, understand, and follow the labeled directions.

Alternatively, homeowners can spray a Bacillus thuringiensis (Bt) product once every two weeks. However, Bacillus thuringiensis is not an effective control for larger caterpillars, eggs, or adults. Bt is a bacterium that kills insects when ingested. There are subspecies of Bt that affect specific types of insects; kurstaki is the subspecies that specifically target caterpillar larvae. Look for product labels that say Bacillus thuringiensis subsp. kurstaki (Btk).

From the MSUE article at this link:

What the box tree moth quarantine means for Michigan homeowners - Floriculture & Greenhouse Crop Production (msu.edu)

I hope this helps!