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Invasive Species: Watch List

Michigan's Invasive Species Watch List

Invasive species on the watch list have been identified as posing an immediate or potential threat to Michigan's economy, environment or human health. These species either have never been confirmed in the wild in Michigan or have a limited known distribution. 

If you think you have found any of these species in Michigan, please report the occurrence via the methods given below by clicking on an individual species name. 

View the watch list as a printable PDF - InvasiveSpecies-WatchList

Asian Longhorned Beetle

(Anoplophora glabripennis)

Watch List - Prohibited in Michigan

The Asian longhorned beetle can attack and kill many tree species including poplar, willow, sycamore, and horse chestnut, but its favorite host are maple trees. The larvae feed in tunnels in the wood of the tree branches and trunks, eventually killing the tree.

More information: Asian longhorned beetle

Asiatic Sand Sedge

(Carex kobomugi)

Watch List

Asiatic sand sedge is a perennial sedge that grows to about a foot tall. It has a triangular stem with brown scales at the base. The leaves are often taller than the club-shaped flowering heads. There are small ridges along the the edge of the leaves, making it feel serrated.

More information: Asiatic sand sedge

Balsam Woolly Adelgid

(Adelges piceae)

Watch List

Balsam woolly adelgid is a sap-feeding insect that attacks true fir trees, including balsam fir and Fraser fir. Repeated attacks weaken trees, cause twig gouting, kill branches and, over the course of several years, cause trees to die.

More information: Balsam woolly adelgid

Beech Leaf Disease

(Litylenchus crenatae and potential associates)

Watch List

Beech leaf disease is associated with the microscopic worm Litylenchus crenatae, a nematode that enters and spends the winter in leaf buds, causing damage to leaf tissue on American beech and European and Asian beech species. Trees become susceptible to other diseases and can die within six years.   

More information: Beech leaf disease

Brazilian Elodea

(Egeria densa - synonyms: Elodea densa, Anacharis densa and Philotria densa)

Watch List - Prohibited in Michigan

Brazilian elodea is a bushy aquatic plant with dense whorls of bright green leaves. It can be found in ponds, lakes, and sluggish rivers and streams.


More information: Brazilian elodea

Carp - Bighead

(Hypophthalmichthys nobilis)

Watch List - Prohibited in Michigan

Bighead carp have a large head with a toothless mouth and eyes that sit below the mouth. They can grow to 5 feet long and weigh up to 90 lbs. Bighead carp are able to establish populations in water bodies with a wide range of temperatures.  Spawning generally occurs following a flood event in large, turbulent rivers.

More information: Bighead carp

Carp - Black

(Mylopharyngodon piceus)

Watch List - Prohibited in Michigan

Black carp have a pointed head that is flattened at the front. Scales are blackish-brown darkening to bluish-gray at the edges, with an almost white belly.  They can grow to 6 feet long and weigh up to 150 lbs. Black carp inhabit large rivers and lakes but require large rivers for reproduction.

More information: Black carp

Carp - Grass

(Ctenopharyngodon idella)

Watch List - Prohibited in Michigan

Grass carp have large scales that appear crosshatched and eyes that sit even with the mouth. They can reach lengths of more than 5 feet and weigh more than 80 lbs. They prefer quiet, shallow waters.

More information: Grass carp

Carp - Silver

(Hypophthalmichthys molitrix)

Watch List - Prohibited in Michigan

Silver carp have a light silver body with a white belly and eyes that sit below the downturned, toothless mouth. They may exceed three feet in length and can weigh up to 60 lbs. These fish primarily inhabit large rivers.

More information: Silver carp

Chinese Yam

(Dioscorea oppositifolia)

Watch List

Chinese yam has slender vines that spiral counterclockwise and pointed, heart-shaped leaves that are often indented on the sides. The bulbils or air tubers are present from June to September and resemble very small potatoes. It has small, white or greenish-yellow flowers that smell like cinnamon.

More information: Chinese yam

European Water Clover

(Marsilea quadrifolia)

Watch List

The European water clover resembles a large four leaf clover, with thin green stalks bearing a single leaf. It can be found in shallow, slow-moving waters.

More information: European water clover

Hemlock Woolly Adelgid

(Adelges tsugae)


These tiny insects secrete white wax as they feed on sap from hemlock shoots and branches. Hemlock woolly adelgid (HWA) feeding can kill needles, shoots and branches, resulting in tree death.

More information: Hemlock woolly adelgid

Himalayan Balsam

(Impatiens glandulifera)

Watch List

Himalayan balsam grows 3-6 feet tall and has purple/red stems that are smooth and hollow. There are 5-10 flowers on each stem and the flowers have 5 petals that are purple, pink, or white in color. The fruit capsules explode when ripe and touched.

More information: Himalayan balsam


(Hydrilla verticillata)

Watch List - Prohibited in Michigan

Hydrilla is a submerged aquatic plant with generally green leaves whorled in a group of 4-8. They have very slender stems that grow up to 30 feet long and branch out considerably near water surface.

More information: Hydrilla

Japanese Chaff Flower

(Achyranthes japonica)

Watch List

Japanese chaff flower is a perennial plant that grows 3-6 feet high with a green, bottle brush-like flower that has no petals.  Leaves are opposite and simple with smooth edges and a pointed tip.

More information: Japanese chaff flower

Japanese Stiltgrass

(Microstegium vimineum)

Watch List

Japanese stiltgrass is a delicate, low-growing grass with stems that sprawl over one another and roots from the nodes. The alternate leaves are short (3-8 cm. long), pale green and lance-shaped with a distinctive, shiny mid-rib, slightly off-center. It prefers forested floodplains but will grow almost anywhere from deep shade to full sun. 

More information: Japanese stiltgrass


(Pueraria montana var. lobate)

Watch List

Kudzu is a vine that extends to 100 feet, with up to 30 vines per plant. It has alternate, compound leaves with three broad leaflets and in late summer produces purple individual flowers that grow in upright clusters.

More information: Kudzu

Marbled Crayfish

(Procambarus virginalis)

Watch List - Prohibited in Michigan

A medium-sized (4 to 5 inch) crayfish with slender or narrow claws.  Streaked or marbled coloration pattern is most visible on the back, or carapace.  In the wild, most range in color from olive to brown, but in captivity, colors can include tan, red or blue.  

More information: Marbled crayfish

Mile-A-Minute Weed

(Persicaria perfoliata)

Watch List

Mile-a-minute weed has light green leaves shaped like an equilateral triangle and small white flowers. They produce a deep blue colored fruit arranged in clusters. Typical infestation areas include stream banks, open space, roadsides, forest edges, and fence lines.

More information: Mile-a-minute weed

Mountain Pine Beetle

Watch List

(Dendroctonus ponderosae Hopkins)

Mountain pine beetle is an aggressive and destructive bark beetle that can infest most pine tree species. The beetles and their larvae tunnel through inner bark, eventually causing tree death.

More information: Mountain Pine Beetle

New Zealand Mudsnail

(Potamopyrgus antipodarum)

Watch List - Prohibited in Michigan

New Zealand mudsnails are an average of 1/8 inch long with 5-6 whorls on their shell. The shells vary from light brown to black. They can tolerate a wide variety of habitats including reservoirs, estuaries, rivers, and lakes.

More information: New Zealand mudsnail

Northern Snakehead

(Channa argus)

Watch List - Prohibited in Michigan

Northern snakeheads can reach up to 33 inches in length. They have a tan color with dark brown mottling, an extended anal fin, a pelvic fin up near the gills and pectoral fins. They have sharp teeth like a pike or pickerel.

More information: Northern snakehead


(Myocastor coypus)

Watch List - Prohibited in Michigan

Nutria are approximately two feet long with yellow or orange colored front teeth. They have thick, rat-like tails covered with bristly hairs.

More information: Nutria

Parrot Feather

(Myriophyllum aquaticum - synonyms: Myriophyllum brasiliensis, Myriophyllum brasiliense, Myriophyllum proserpinacoides and Enydria aquatica).

Note: "Dwarf parrot feather" and "dwarf red parrot feather" are common names for a dwarf selection sold in trade. 

Watch List - Prohibited in Michigan

Parrot feather has spikes of stiff, feathery leaves that grow in whorls of 4-6. It has bright green upper stems that emerge up to one foot above water and small inconspicuous white flowers where leaves attach to the section of stem above water.

More information: Parrot feather

Red Swamp Crayfish

(Procambarus clarkii)

Watch List - Prohibited in Michigan

Red Swamp Crayfish have dark red color with bright red raised spots - they look like small lobsters. They can live in a variety of permanent freshwater habitats. They feed heavily on snails, fish, amphibians, and plants.

More information: Red swamp crayfish

Spotted Lanternfly

(Lycorma delicatula)

Watch List

The spotted lanternfly sucks sap from the stems and leaves of orchard trees, grape vines, oaks, pines and other host plants. Feeding can weaken the plant and eventually contribute to its death. Trees will develop weeping wounds that attract other insects and excreted fluids from spotted lanternflies can cause mold growth on plants.  

More information: Spotted lanternfly

Thousand Cankers Disease

(Pityophthorus juglandis + Geosmithia morbida)

Watch List

Thousand Cankers Disease involves an insect native to the southwestern U.S. The disease affects black walnut trees, a valuable economic and ecological resource in Michigan.

More information: Thousand cankers disease

Water Chestnut

(Trapa natans)

Watch List - Prohibited in Michigan

Water chestnut has green floating leaves with sharply serrated edges that form a densely crowded rosette. They produce small, white 4-petaled flowers and a woody nut surrounded by sharp barbed spines.

More information: Water chestnut

Water Hyacinth

(Eichhornia crassipes)

Watch List

Water hyacinth is a free-floating perennial herb with short, bulbous leaf petioles and has round, leathery leaves arranged in whorls of 6-10. It has distinctive air bladders that keep the leaves afloat.

More information: Water hyacinth

Water Lettuce

(Pistia stratiotes)

Watch List

Water lettuce is a free-floating plant with a rosette of leaves that resembles an open head of lettuce. The leaves are thick, ridged, rounded at the end, light green, and have short, white hairs. It produces small, white to pale green flowers. Many feathery roots dangle under the rosette.

More information: Water lettuce


Watch List

(Ludwigia grandifolia, Ludwigia peploides and Ludwigia hexapetala) 

Invasive water-primrose species are aquatic plants that can thrive and spread in shallow water areas including wetlands and shorelines. Water-primrose can grow quickly, with both upright stems and horizontal runners crowding out important native vegetation. 

More information: Water-primrose

Water Soldier

(Stratiotes aloides)

Watch List - Prohibited in Michigan

Water soldier is a submerged aquatic plant that becomes buoyant during the summer. Its leaves are 40cm long, bright green, sword-shaped, have sharply serrated edges, and form a large rosette. The roots may or may not be attached to mud. This plant looks similar to an aloe plant, spider plant, or top of a pineapple.

More information: Water soldier

Yellow Floating Heart

(Nymphoides peltata)

Watch List - Prohibited in Michigan

Yellow floating heart has bright yellow flowers with 5 petals located above the surface of the water. Leaves are circular or heart shaped and are alternately arranged on the stem but oppositely on the flower stalk.

More information: Yellow floating heart