This article originally appeared in a June 2024 edition of the DNR News Digest

Summer is the busy season for most creatures, including invasive species like spongy moth, box tree moth and Japanese beetle just to name a few. Many of these species are established in Michigan, meaning they’re here to stay, but it’s a good idea to know what to look out for and help mitigate their effects on local environments. While these bugs are just following their natural instincts, their presence can affect the delicate balance of ecosystems, making it harder for native species to thrive. 

Spongy moth caterpillars are emerging in some areas of the state, so know how to spot and manage them. This species is known for its defoliation, often leaving trees vulnerable to diseases and other pests, which may lead to tree mortality.

Box tree moth caterpillars feed mostly on boxwood, hence their name, and heavy infestations can defoliate host plants. Once the leaves are gone, larvae consume the bark, leading to girdling and plant death. Because there are no natural predators in Michigan, box tree moth can reach large population densities, limited only by available food sources.

Gardeners well know the sight of Japanese beetle, another prolific defoliator. Adults emerge from their grub stage in June and July, feeding on plants throughout the rest of summer. They can skeletonize leaves and flowers of ornamental plants and trees and can damage crops.

Make sure not to move firewood, too; it can transport invasive species and diseases into new areas. If you’re planning to have a fire, buy your wood locally to where you plan to burn.

Keep up to date with Michigan invasive species, including those on the watch list. If you see an invasive species that hasn’t been established, use the Midwest Invasive Species Information Network (MISIN) online reporting tool or download the MISIN smartphone app and report from your phone.

Want a more detailed look into invasive species? Check out the recent Showcasing the DNR story and sign up for a NotMISpecies webinar.

Find more information, including a full list of invasive species in Michigan and management practices, at Michigan.gov/Invasives.