The aliens have landed in Wisconsin! You may see them and not even know they are aliens. These invaders are actually exotic plants and animals that have been introduced to our state from other countries or habitats on purpose or by accident. They can cause all kinds of problems for plants and animals that have always lived in our state. Read these stories and find out how to pick aliens out of a crowd, learn how to identify impostors, and how to help exterminate these alien invaders before they take over!

photo of a pile of zebra mussels
Gypsy moth caterpillar
The gypsy moth (caterpillar) is a serious defoliator of trees and shrubs in North America.
Read More
sea lamprey in an aquarium with their mouths attached to the aquarium glass
Sea lampreys are members of an ancient family of "jawless fishes" that were around before the dinosaurs.
Read More
Spiny Water Flea
Spiny water fleas eat zooplankton and compete directly with small fish that also need to eat it.
Read More
photo of spongy moth showing feathery antennae
When spongy moths have an "outbreak," the caterpillars defoliate trees (eat all the leaves).
Read More
a huge pile of zebra mussel shells
These invasive critters remove incredible amounts of food from the water.
Read More
Emerald Ash Borer on leaf
Once these invaders get into a tree, the tree always dies.
Read More
Eurasion Water-Milfoil on white background, Photo Credit: Flora of Wisconsin, Paul Skawinski, CC BY-SA
Preventing milfoil from reaching a lake or spreading is extremely important.
Read More
Garlic Mustard
No—It's not something you put on your sandwich
Read More
Close up of leafy spurge
Leafy spurge is considered a noxious weed under Wisconsin law.
Read More
Multicolored Asian Lady Beetle
The multicolored Asian lady beetles look like common "ladybugs."
Read More
Blooming purple loosestrife (Lythrum salicaria) growing at a garden
Purple loosestrife is a non-native invasive plant that has taken over some wetland areas.
Read More
photo of a quagga mussel
A quagga mussel feeds all year, even in winter.
Read More
Round Goby
This invader is a bottom dwelling fish with a large head, resembling a tadpole.
Read More
photo of rusty crayfish
Most alien invaders come from another country, but not this one.
Read More
Knapweed close-up in field
Spotted knapweed secretes chemicals into the soil that kill surrounding plants.
Read More
Wild Parsnip in field
Scientific name: Pastinaca sativa
Read More