Invasive Animals


  • Mute Swans Mute swans are an invasive non-native species that pose a growing threat to native animals, habitat and people. Their numbers are well above an acceptable range, requiring the DNR to increase management efforts. The DNR needs your help to decrease this invasive population. To learn more, visit

Crustaceans and Mollusks

  • Rusty Crayfish The rusty crayfish is considered a threat to Michigan's native crayfish population, and could have environmental and economic impacts on local areas. The major threat is the reduction of aquatic plant beds and the species that live in these communities. Many fish may lose nesting areas and shelter when aquatic plant beds are reduced.


  • Northern Snakehead Fish (Channa argus) The Northern snakehead is native to the waters of China, and possibly Korea and Russia. The snakehead has the ability to move from one body of water to another by using its pectoral fins. Snakehead have no natural predators in the U.S. and they are voracious carnivores.
  • Asian Carp (three species) Asian carp are viewed as a potential ecological problem if they gain access to the Great Lakes. The bighead and silver carp eat plankton and grow to large sizes. Fisheries biologists are concerned they will out-compete native species for food and habitat. See the DNR's Asian carp Web page at for information about identifying Asian carp, an Asian carp fact sheet, frequently asked questions and more.


  • Asian Longhorned Beetle PDF icon

    Native to China and other Asian countries, the Asian longhorned beetle leaves large tunnels, created by larvae, in thousands of trees which cause branches and stems to break and die which can often lead to tree death.

  • Hemlock Woolly Adelgid PDF iconThis small aphid-like insect feeds on several species of hemlock (Tsuga spp.) greatly injuring them. By sucking plant juices and injecting a toxic saliva while feeding, this Asian insect causes needles on infested branches to desiccate, turn a grayish-green color, and fall.
  • Emerald Ash Borer In southeastern Michigan in 2002 the emerald ash borer was discovered feeding on ash. Ash trees native to North America appear to have little to no immunity to this insect which is significantly impacting the vigor and survival of Michigan's 700 million white, green and black ashes.
  • Balsam Woolly Adelgid PDF iconFeeds on stem, branches and twigs. During the balsam woolly adelgid's feeding, it injects a salivary substance into the tree causing gall-like formations on the twigs and branches (gouting). Gouting may progressively weaken a tree over a long period of time.


  • Feral Swine Like other Midwestern states, Michigan is experiencing a growing problem with feral or wild swine. Feral swine are a problem for two main reasons - they can host many parasites and diseases that threaten humans, domestic livestock and wildlife; and they can cause extensive damage to forests, agricultural lands and Michigan's water resources. To learn more about Michigan's feral swine problem, visit