Michigan has 10 insects on its invasive species list.
Many of these insects threaten trees and plants across the state.
If you believe you have found one of these invasive insects, you can report it through the Midwest Invasive Species Information Network. Just click here and search for the insect.
Spotted lanternfly
If you see one, catch it and kill it.
Each spotted lanternfly can lay an egg mass containing around 30-50 eggs. If you see an egg mass, squish it.
These insects feed on more than 70 different plants including grapes, apples, hops, and hardwood trees. They suck sap from host plants while secreting large amounts of sugar-rich, sticky liquid called honeydew.
The honeydew, and resulting black sooty mold, can kill plants and foul surfaces. The honeydew attracts pests like yellow jackets, flies and ants.
There are some people online who are using water bottles or other plastic cups to capture the spotted lanternfly when they’re on trees. You simply put the mouth of the bottle around it and the lanternfly will fly into the bottle.
If you find any spotted lanternfly, report them to the DNR at www2.dnr.state.mi.us/ors/Survey/38.
Read: Invasive spotted lanternfly found in Michigan for first time: What to know
Japanese beetle
The Japanese beetle is widespread throughout Michigan.
Adult beetles are about 3/8 inch in length and have a bright, metallic green head and body and metallic brown wings. Its legs are a darker green. There are 12 tufts of white hairs surrounding the edges of the abdomen.
Grubs or larvae are about 1/16 to 1/4 inch in length, are white and have three pairs of legs. Adult beetles emerge in June or July and feed throughout the summer.
The grubs live underground and feed on grass roots. They leave brown patches in lawns. The adults feed on foliage, flowers and fruit, including tree fruits, small fruits, ornamentals, garden vegetables, soybeans and corn.
Spongy moth
Spongy moth caterpillars emerge from tan, fuzzy egg masses in April and feed on leaves through late June.
The caterpillars are hairy and have a yellow and black head, five pairs of blue spots, followed by six pairs of red spots. Mature caterpillars are 1.5 to 2 inches in length.
If you find leaf debris and small, round frass under trees, that’s an indication of a spongy moth infestation.
Male moths’ wings have a wavy pattern of brown to dark-brown and span 1.5 inches. Female moths are larger than males and do not fly. The females have white to cream color wings with wavy black markings.
The caterpillars are of concern because they can defoliate trees, leaving them vulnerable to diseases and other pests, which can kill trees. Caterpillars can be blown by the wind to other trees.
Read: Invasive moth found in Michigan gets new name because of derogatory term
Emerald ash borer
The emerald ash borer is known to be established in Michigan’s Lower Peninsula, and has been detected in Michigan’s Upper Peninsula.
It has a bright, metallic green body with purple abdominal segments under its wing covers. It’s about 1/2 inch long as an adult. It can fit on the head of a penny. The larvae are worm-like. They create a d-shaped exit hole in trees.
Adults feed on the foliage of ash trees while the larvae tunnel and feed on the underside of the bark, which cuts off the transportation of nutrients and water to the tree.
They were first discovered in Michigan in 2002, and have killed tens of millions of ash trees in the state. They have killed trees in forests and neighborhoods.
Adults typically only fly half of a mile, but they can be transported through infested firewood to non-infested areas.
Brown marmorated stink bug
The brown marmorated stink bug is established in Michigan.
It’s a 0.5-0.625-inch shield-shaped insect that uses its piercing mouthparts to suck plant juices from fruits, seed pods, and nuts on many plants.
It was accidentally brought to North America from Asia in 1996. It was first detected in Michigan in 2010, and is now a major pest for farmers.
Stink bugs have since been found in all Michigan counties, but are well established in the southern part of the Lower Peninsula.
The good news is that stink bugs will not cause structural damage or reproduce in homes. They also do not bite people or pets.
They are not known to transmit disease or cause physical harm, but they have their name for a reason -- they produce a pungent chemical that, well, it stinks.
Read more: Let’s talk about Michigan stink bugs: Why are they here? What should you do about it?
Asian longhorned beetle
It’s an invasive, wood-boring beetle that attacks 12 types of hardwood trees, including maples, elms, horse chestnuts, birches, and willows. It doesn’t have any predators or diseases to keep the population down.
When it’s in its larval stage, it feeds inside tree trunks and branches during the colder months. It creates tunnels as it feeds, and then chews its way out as an adult in the warmer months.
Trees that have been infested will not survive.
Although the beetle has not yet been discovered in Michigan, officials say it’s “crucial we keep an eye out for it.” Discovering early signs of infestation can prevent widespread damage to the state’s forest resources, urban landscapes, and maple syrup production.
Look for the following signs when you’re outside:
- Round exit holes, about the diameter of a pencil, found in tree trunks and branches.
- Shallow oval or round scars in the bark, where the adult beetle chewed an egg site.
- Material that looks like wood shavings lying on the ground around the tree or in the branches.
- Dead branches or limbs falling from an otherwise healthy-looking tree.
Adult Asian longhorned beetles are large and range from 3/4 to 1 1/2 inches in length. That doesn’t include their long antennae. They are shiny black and have random white blotches, or spots.
Read more: Start checking trees for signs of Asian longhorned beetles: What they are, why they’re a threat
Balsam woolly adelgid
Balsam woolly adelgid has been detected in Michigan.
It infests true fir trees, including balsam, fraser and concolor (white) fir in forests and landscapes in Michigan.
It’s a sap-feeding insect and its repeated attacks can weaken trees, cause twig gouting, and causes trees to die over the course of several years.
Michigan officials say to watch out for the following signs:
- Tiny one-to-two-millimeter white woolly tufts on the lower trunk of the tree and possibly on large branches in the spring and summer.
- Swelling and distortion of the twigs, commonly called “gout.”
- Flagging - a branch or branches that turn brick-red.
- Tree crowns that become narrow and misshapen with few needles.
Read: Invasive insect that attacks true fir trees found in Missaukee County
Hemlock woolly adelgid
Hemlock woolly adelgid has been detected in Michigan.
It infests eastern hemlock trees and has been found in Michigan in forests and landscape settings. Eastern hemlock is found naturally in moist forest environments and along streams and water bodies.
The hemlock woolly adelgid sucks sap from the hemlock needles, killing needles, shoots and branches. Infested hemlocks become less vigorous and may turn grayish-green. If it’s untreated, it can kill a tree within 4-10 years.
Michigan says to watch out for the following signs:
- Small, round, white, cottony masses, 1/16″ to 1/4.″
- Found on the twig at the base of the needles on the underside of hemlock tree branches.
- Present year-round but most visible November through July.
- Note that hemlock woolly adelgid infests eastern hemlock trees, not pines or spruces.
Read: Time to check Christmas trees for hemlock woolly adelgid
Mountain pine beetle
The mountain pine beetle is on Michigan’s invasive species watch list, but has not been detected in the state.
This bark beetle is described as aggressive and destructive. It can infest most species of pine tree. The beetles and their larvae tunnel through inner bark and eventually will kill the tree.
This beetle is hard to identify. Michigan suggests looking for these signs:
- Popcorn-like globs of brown, pink or white pitch on the tree’s trunk.
- Red frass, resembling fine sawdust, on bark crevices or at the tree’s base.
- Yellow to red needles in the tree’s crown in the summer.
- Evidence of woodpecker feeding, such as missing patches of bark.
- Galleries under the tree’s bark.
If you find signs of this beetle, you should note the location and take photos. Report any findings to the Michigan Department of Agriculture and Rural Development at MDA-Info@Michigan.gov, or use the Midwest Invasive Species Information Network’s online reporting tool.
Box tree moth
The box tree moth has been detected in Michigan.
They are a concern because their caterpillars feed mostly on boxwood, and heavy infestations can defoliate host plants. Once the leaves are gone, the larvae consume the bark. This will kill the plant.
The box tree moth has no natural predators in Michigan, which means they can grow large populations that are only limited by food sources.
The box tree moth can move around 5 miles per year -- which means when it’s found out of its native range, it got there through importation and sale of boxwood and box tree nursery stock.
As of Dec. 11, 2023, the Michigan Department of Agriculture and Rural Development has expanded the interior quarantine for invasive box tree moth. The quarantine now inclues the entire counties of Clinton, Eaton, Ingham, Jackson, Lenawee, Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne.
In the quarantine, the whole plant, plant parts, and nursery stock of the genus Buxus, including living and dead plant material, cannot be moved outside of the quarantined area.
Wreaths, boughs, and grave blankets from Buxus are not quarantined if moved from October 15 through Jan. 1.
Signs of box tree moths include the following:
- On boxwood and box tree species (Buxus spp.) - green and yellow caterpillars with white, yellow, and black stripes and black spots.
- Loose webbing in the area of caterpillar activity.
- Evidence of feeding on edges of boxwood or box tree leaves or skeletonization of leaves.
- White moths with a brown border and distinctive white comma-shaped mark on each forewing.
- Less frequently - moths that are entirely brown except for the white mark on each forewing.
- Clusters of 5-20 pale yellow eggs on the leaves of boxwood or box trees.
If you see signs of box tree moth or its caterpillars, you should take photos and submit a report through Michigan’s Eyes in the Field online reporting system.