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Invasive Species of Iowa

Author: john-kraus

Post on 21-Feb-2017




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Invasive Species of Iowa

Invasive Species of Iowa

Hello! Todays presentation is about the invasive species of Iowanon-native plants and animals that have spread aggressively into natural areas in our state. Id like to focus on basic identification today so that all of you are aware of what is out there. Well start with the animal and then well talk about plants found in open areas, then well discuss aquatic organisms, and next well talk about woodland species. At the end Ill describe a few of the techniques that folks can use to control invasive plants. 1

Common Carp at Lake Meyer

There are four types of Eurasian carp found in Iowa: common carp, grass carp, silver carp, and bighead carp. Each species has different characteristics. Grass carp consume aquatic vegetation and were deliberately introduced to help control algae blooms. In turns out they are a bit too good at their jobs. Many species of native aquatic plants (and animals that depend on the plants) are under threat due to excess consumption by grass carp. Furthermore, the lack of aquatic plants has increased the turbidity of many lakes and ponds. They are a popular food fish in some areas.

Common carp have been established for much longer than the other 3 species (since the 1800s). They feed on aquatic plants as well, and they are often blamed for stirring up sediment whilst feeding. They are not as popular as a food fish.

Silver and bighead carp are relatively recent arrivals. They were established in the Mississippi River roughly between 1970-1990. They are plankton-eating, filter-feeders and as such are considered to be a grave threat to native fish species and aquatic ecosystems. Great effort is being focused on preventing these species from getting established in the Great Lakes.

Black carp are probably still in the southern part of the Mississippi River, but evidence suggests that they may spread upwards and into Iowa. This species feeds on snails and mussels; these organisms are already under threat, so the introduction of a new predator is not ideal.2

This guy is a red-eared slider. This turtle is native to the southern Mississippi River Valley and many of its tributaries, but it has been raised as a pet and released in many other places around the world. The Teenage Mutant Ninja Turtles may have had something to do with it. There dont seem to be any major problems in Iowa, but theres a good chance that some of them are around. The primary problem with these animals is that they are going to compete for the same ecological niche as our native turtles. In the Southeastern U.S. they are inter-breeding with the native yellow-bellied sliders.4

The zebra mussel! This mollusk has taken the Great Lakes and Mississippi River by storm. Mussels are usually a great thing to have in our bodies of waterthey filter both nutrients and pollutants, play an important role in the food chain, and act as water quality indicators. As for zebra mussels, they do the same things, they are just too good at it. They out-compete native mussels and consume so many nutrients that they can make a lake or river nutrient-poorwe usually have the opposite problem here in Iowa, but neither is good. They also junk up pretty much anything man-made ranging from docks and boats to critical water-intake pipes.

FYI, they are originally from Eastern Europe. They are tiny, about the size of a fingernail, but they make up for their size in numbers. Their larvae are called Veliger. 5

Yes, thats an earthworm. Believe it or not, the ubiquitous nightcrawler is not from around these parts. There are native earthworms in the SE and Pacific Northwest, but not in our neck of the woods. They may have once been here, but they havent been back since the most recent batch of glaciers. The 15 non-native earthworms came to the Midwest via ship ballast, imported plants, and as fish bait. 6

So, whats the problem with earthworms. In the woodlands earthworms consume lots of leavestoo many for the good of the forest! Many plants rely upon the layers of leaves duff for habitat and nutrition. Earthworms are part of the problem with nutrient cycling in Iowas woodlandsnutrients are being processed and transported more quickly than in the past. The nutrients are often leached into the groundwater or washed into streams and rivers.

The good news is that earthworms dont travel fast on their own. Researchers estimate about mile in 100 years, fyi. So we can a difference by doing our best not to introduce earthworms or large quantities of soil. Just so you know, red wiggler compost worms are not winter hardy in this area, so we dont need to worry about them.7

Iowas Most Costly Invasive Species

The European Corn Borer! Originally a pest for millet and sorghum growers, in Iowa it takes to corn. Before the advent of genetically modified corn with genetics from the bacterium Bacillus thuringiensis, it was quite the pest causing damage to leaves, stalks, and the ears. 8

Another Agricultural Pest

The cabbage white butterfly! It feeds on cabbage and all of the other members of the brassica family are fair game. The larvae is small and green. Good control methods in your garden include putting young plants underneath a row cover and planting for fall harvest. Sulphur butterflies may have light-colored morphs that look similar, but the cabbage white will always have those dots on the forewings.9

Headed in our Direction

The European gypsy moth! Not a picky eaterits larvae consumes at least 500 different types of tree and shrub leaves. It was introduced to the U.S. in 1869 as a candidate for silk production. It escaped from a home in Massachusetts and has been moving west since then. It moves up to 13 miles per year; the larvae actually hitch a ride on windy days after swinging from silken threads.

Transporting firewood can dramatically increase its spread. It has reached Eastern Wisconsin, so its not far away.

The problem with this critter is that the larvae can dramatically defoliate and even kill trees. Its favorite food trees are oaks, but it will select plenty of other species along the way. 10

The elm bark beetle. At first glance it looks a bit like a june bug, but it is quite small. There is a native species as well as 2 Eurasian species. The main things to know is that these insects are the vector for a fungus that causes Dutch Elms Disease. The disease probably originated someplace in Asia, and it was identified and researched by Dutch scientists around 1921. It caused a massive die-off of elm trees in Iowa during the 1970s and 1980s. Elm trees endure in Iowa, but they no longer reach the size or age of their ancestors. Hybrids with a bit of genetics from Asian elm species can be planted as street or yard trees. 11

An Emerald Menace

The Japanese beetle. A serious pest on over 200 plant species in the US, including roses, grapes, birch trees, and basswood trees. They feed upon the leaf material between veins, so they do create a distinctive form of damage to the plants. They are well established throughout the Northeastern U.S. and are making good progress in parts of the Midwest.12


The Asian ladybug. Perhaps it should go by the name Harlequin Ladybug due to the variety of spots and colors it can have. Note the w or m-shaped marking between the head and the thorax (pronotum). This marking helps distinguish this insect from native ladybugs.

They can be a pest in our homes, but they do some good by consuming large numbers of soybean aphids. 13

Native lady beetles are never a nuisance and hibernate under decayed tree bark out in the woods. They dont bite or stink.

All ladybird beetle larvae are beneficial. They eat aphids and scale insects and other bugs that cause gardeners headaches.A

Another Pest headed for the Midwest

The Asian long-horned beetle. Another opportunistic, hungry insect headed our way from Northeast Asia via the Northeastern USA. It probably arrived here on wooden packing material. Maple trees are its favorite, but it will gladly eat elms, willows, birch, and several other common tree species if need be. Larvae are true wood borers that create extensive galleries in both the cambium and the heartwood.

The good news is that this insect has been eliminated in a few locations when it was detected early in the process. There are still active infestations in Massachusetts and Ohio.16

The brown marmorated stink bug. Marmorated means marbled by the way. A native to northeastern Asia that has become an agricultural pest, particularly for orchards. The striping on the antennae and the sides of the abdomen help distinguish it from native stink bugs. Like the Japanese lady beetles, this bug will take refuge in houses during the winter months and raise a stink.

This bug has been found in Iowa and a few neighboring states, but big problematic populations havent formed yet. 17

Another Emerald Menace

The infamous emerald ash borer! This beetles larva kills ash trees large and small by tunneling around the trees cambium and girdling the tree. Note the D-shaped exit holes that the larvae make as they emerge and take on their adult form. Ash trees make up a huge part of our urban treescape in Iowa, and it is a very common tree in our woodlands as well.18

This is a map of emerald ash borer locations in Iowa and neighboring states. As you can see, this insect has been found in Allamakee County and several neighboring counties in Minnesota and Wisconsin. Eastern Winneshiek County is within the IA DNRs 15 mile treatment circle. This means that it is recommended that we begin removing and replacing ash trees so that workloads will not be overwhelming when a serious infestation gets going.

The insect can travel only a few miles per year on its own, but it has been known to hitch a ride on firewood.19

Another Familiar Pest

And here we have another pesky bug that invades our homes each fallthe box elder bug. They do feed on box elder, maple, and ash trees, but they do not do significant damage.

This animal is native to Iowa. I would call it a native nuisance. Can anybody else think of native animals that can make themselves a nuisance? It really depends on your perspective; many people dislike spiders and insects as a group. Id say mosquitoes, biting flies, and ticks would be the ones I would get rid of. Canadian geese, house wrens, brown cowbirds, etc. 20

Pigeons and Doves

One is native and two are not. Do you know their names and where they are from?21

Clockwise from top-left: house sparrow, song sparrow (black spot on chest), field sparrow (pinkish bill), and female red-winged blackbird.

House sparrows may be the most widely distributed wild bird. They originated in the Middle East and moved along with humans and agricultural landscapes to Europe and much of western Asia. They have become successful transplants in Australia, Africa, and the Americas.

They can be found in almost any type of habitat excluding areas of large dense forests and tundra.

You will often see them in flocks looking on the ground for seeds.

If you find a really full, messy nest in a nest box, it probably belongs to a house sparrow.


The common grackle. Native. Iridescent head and size distinguishes it from a crow.23

European starling. Introduced in the late 1800s in New York City by a person (Acclimitization Society) who wanted to have all of the animals described in William Shakespeare. They have taken the country by storm and have displaced many of our native songbirds via competition for resources. They also can be agricultural pests, and roosting areas in urban areas get awfully messy. They are exempt from the Migratory Birds Treaty, like the house sparrow.24

Believe it or not, feral hogs are starting to become a problem in southern Iowa. Some hogs have ranged freely and become feral since settlement days, but the problem has accelerated with the introduction of European wild boars for meat production and sport hunting. These hardy hogs form groups called Sounders of about a dozen animals. The problems associated with feral hogs are many; rooting and wallowing destroys groundcover and increases erosion, prolific resource consumption, and the ability to act as disease vectors.

Another domesticated animal that has become feral in surprisingly large numbers is the house cat. 25

Managing Invasive Animals Dont release domestic or non-native animals into the wild

Stop aquatic hitchhikers

Dont transport or purchase non-local firewood

Stay informed

Invasive Plants in Open Areas

Open areas cover a lot of territory in Iowawere talking native prairie grasslands, cow pastures, roadsides, and construction areas. As you probably know, invasive species are most likely to gain a foothold in places that have been disturbed; bare soil, plentiful sunlight, and reduced competition allow invasive seedlings to thrive.

I am going to cover some of the most infamous invasive plants, but this wont be comprehensive. Read from multiple sources, including neighboring states. There are many species that are in southern Iowa or neighboring states that havent become pests in NE Iowa yet.27

Bull Thistles can be a big prickly problem

Lets start with one that most of you have probably seen beforethistles. This is the bull thistle; the most common large thistle in our area. Biennial plant that colonizes disturbed ground. A ruderal species. It is native to Europe, and its the National Flower of Scotland.


Bull Thistles can grow six feet tall and flower abundantly in late August


A favorite source of nectar for bees and butterflies. Goldfinches and a few other birds enjoy eating thistle seeds. Livestock and farmers generally do not have nice things to say about bull thistles. This species is on the State of Iowa Noxious Weeds List. Each County has the power to appoint a weed commissioner to control these weeds, especially when weeds from one persons property are threatening to spread into adjacent property.30

Musk Thistles look a lot like Bull Thistles, growing just as tall.


Musk Thistles have purple flowers that bloom in mid-July. Note the spiny collar at the base of that blossom.

They also have a bit of a silvery-blue tinge to them that is distinct from the bull thistle. The spiny collar on the musk thistle reminds me a bit of a lions mane. Maybe you will remember the difference by telling yourself bull thistles smell sweet but lion thistles smell musky.32

Canada Thistles are the smallest thistle plants around here, but they present the biggest control challenge.

Canada thistles are actually from Europe and northern Asiadont ask me how the Canadians got blamed. 33

Canada Thistles normally grow about knee high. Unlike other thistles that spread via seed, Canada Thistles primarily spread from their roots.

The laterally spreading roots may be known as rhizomes or stolons34

Canada Thistles can create huge colonies that produce enormous amounts of seeds in late July.

Unlike bull and musk thistles, Canada thistles are more likely to spread and persist in prairie plantings.35

Common Teasel

Introduced in the 1800s, it was used to raise the nap on cloth as part of the textile industry. It has also been used as an ornamentalstands often originate from old cemeteries as well as along the interstate highway system. 36

Dames Rocket, aka Phlox

This is one of the prettiest flowers that shows up along Iowa roadsides in late spring. The plumes can be pink, purple, or white. It isnt on the top of my list of weeds to hate, but you ought to know that it is non-native and somewhat invasive. There are less common native varieties of phlox.37

Bifid Hemp Nettle

Poisonous for human consumption, noxious weed in Alaska and some parts of Canada, annual plant that invades disturbed areas in pastures and open woodlands. Ive seen quite a bit of this plant in the cow pasture near my home. 38

Wild Parsnip is another big problem plant in Iowa. Growing head high, yellow flower umbels form in late June.


Wild Parsnip plants are abundant in area ditches and old fields, and can hurt people a lot worse than thistles.


If your skin touches a Wild Parsnip plant when the suns shining, youre almost certain to get a chemical burn.


Even small first year plants can burn you, but you can also eat them.


Wild Parsnip

Parsnip roots in the produce section are much plumper.43


Another yellow flowered plant, often found in pastures by old homesteads. It was once used for worming animals. It is somewhat invasive and is toxic for human consumption.44

Leafy Spurge

Another yellow flower. Thankfully I havent seen this one around NE Iowa, but it can be found elsewhere in the state. It tends to invade dry, open areas where competition is a bit more limited. Grazing by animals large (goats and sheep) and small (several types of beetles) suggest that biological control may work in some areas.45

White Sweet Clover has white flowers and is common in road ditches too. It is one of several invasive legumes in open areas.

This plant is also successful at invading high quality prairie plantings.46

Yellow Sweet Clover doesnt spread quite as fast as its white cousin, but watch it anyway.


Crown Vetch is another invasive legume plant common in grassy areas

Yet another plant that can make forays into prairies.48

Crown Vetch leaves are somewhat pea-like.


Crown Vetch flowers are actually quite attractive and were widely planted as a roadside landscape plant years ago.


Crown Vetch populations exploded into surrounding areas after colonization.


Birdsfoot Trefoil

Not as invasive as crown vetch, but it is a similar non-native legume planted primarily for erosion control along roads and also as livestock forage. Mowing or spraying are the preferred control techniques; prescribed fire increases seed germination, so it would take an intensive fire regime to control this plant. The clusters of seed pods look a bit like a birds foot.52

Reed Canary Grass is another problem plant in wet areas. This is a tall grass, growing up to seven feet.


Reed Canary Grass spreads by rhizomes and forms very large dense colonies, killing off the competition.


Reed Canary Grass blooms in early July.


Most wildlife avoids the difficult mats of Reed Canary Grass, but this hungry spider found a home on one plant.


Monocultures, like this Reed Canary Grass stand, are never a good thing in nature as they suppress diversity.


Smooth Brome

Most common grass used along roadsides and other erosion control areas. It does provide thick groundcover quickly, but native grasses can offer equal or even superior erosion control once they have been established.58

Chinese Silver Grass, Miscanthus sinensis

Also called Pampas Grass due to its resemblance to the plumes on a common grass on the Pampas plains in Argentina. Primarily invasive vegetatively, but it does produce some seed. Its somewhat common in ditches and as part of ornamental plantings.59

Other Non-native GrassesCool Season Pasture Grasses: quack grass, orchard grass, timothy, tall fescue and meadow fescue

Dry land grass:western cheat grass

Wet, acidic soils:Japanese stilt grass

Invasive Species in Wetlands

Purple Loosestrife! Native to the Eastern Hemisphere, this plant can be quite invasive in wetland areas. The good news is that 5 beetle species are being used as biological controls for this plant with some good success.61

Invasive Species in Woodlands


Garlic Mustard may be the nastiest alien in our woods today


Garlic Mustard plants in year one have scalloped round leaves in a basal rosette.


Second-year Garlic Mustard plants bolt and form white flowers in late May.


Garlic Mustard was brought to this country as a garden vegetable, but it escaped to take over the woods. Enjoy!


Multiflora Rose was brought to this country on purpose too, planted as a pretty living barbed-wire fence.


Multiflora Rose leaves look like any regular rose.


Multiflora Roses are snow white, blooming in June.


Multiflora Rose hips are scarlet red and decorate the plants by late summer.

Hungry songbirds freely spread their seeds.


Multiflora Rose makes an impenetrable tangle in infested timbers


Japanese Barberry is another thorny woodland invader.


Japanese Barberry has small roundish clasping leaves and forms oblong fruits.


Japanese Barberry berries turn red as Rudolphs nose in autumn.


Burning Bush


This showy plant has escaped from peoples backyards into a variety of woodland habitats. One distinguishing feature that isnt shown in the photo are corky wings that grow along both sides of some of the older stems. Dont plant burning bush in your yard without determining whether it is invasive or not. A good native alternative is the Wahoo Bush, which is as fantastic as its name suggests.76

A Japanese Barberry jungle.


Japanese Bamboo is incredibly invasive and almost impossible to eradicate.


Japanese Bamboo was brought here as a novel hedge plant, but it quickly grew out of control.


Japanese Bamboo has distinctive red stems. The plant spreads by underground roots or even detached plant parts.


Japanese Bamboo flowers in midsummer


Stinging Nettle, otherwise known as Burning Weed, can form extensive patches in open woodlands.


Stinging Nettle leaves contain calcium oxalate crystals that burn when they penetrate our skin surface


Autumn and Russian Olive

I bet you didnt know that we have olive trees in Iowa! Unfortunately, it doesnt seem like either are good for eating. I havent seen either of these two trees in NE Iowa yet, but they may be on their way from southern Iowa. Autumn olive has juicy red fruits, and Russian olive has mealy yellow ones. 84

Tartarian Honeysuckle is a real aggressive shrub all across the Midwest.


Like a broken record, Honeysuckle was brought here on purpose, planted for its pretty fragrant flowers, blooming in May.


By midsummer, red or orange translucent fruits are forming. These berries are too insipid for people, but birds eat them.


Native Honeysuckle Lonicera dioica

Spread by birds, Honeysuckle shrubs sprout almost anywhere and shade out surrounding plants.


This woodland understory is totally overgrown with Honeysuckle, showing up as the green growth in spring.


Honeysuckle can cause problems out in open areas too, taking over fencelines and even fallow grasslands


Spring wildflowers like Bloodroot will be smothered out by these screening Honeysuckle shrubs


Honeysuckle sprouts multiple stems, making control difficult


This area has just been cleared of Honeysuckle bushes


European Buckthorn can grow as either a shrub or small tree out in the woods.


Buckthorn was brought from Europe as a yard hedge and landscape plant, but took off in our timbers.


Identify European Buckthorn by scraping back the bark, exposing the orange interior.


European Buckthorn is not called a thorn for nothing. Stems end in a sharp spine.


European Buckthorn leaves often look glossy. They leaf out before native trees in spring and stay green late into fall.


European Buckthorns produce purple berries in autumn. Birds eat them, get sick and expel them into new areas.


Amur Maple

Commonly planted in yards. Very pretty, but it could become invasive. Look-A-Likes: Amur maple is most easily mistaken for a small red maple (Acer rubrum). The terminal leaf lobes in Amur maple tend to be more elongate. The undersurface of Amur maple leaves are light green, while red maple tends to have a much paler light color. Amur maple flowers are white and fragrant, while red maple flowers are non-fragrant and red. Amur maple samaras have nearly parallel wings and persist into late fall, while red maple samaras have more angled wings and tend not to persist. 101

More Invasive Species in our AreaIowa DNR

Minnesota DNR

Wisconsin DNR

Ridding our woods and fields of non-native weeds is time-consuming and expensive


Tordon is a cheap reliable tree killer.


Coat the living tissue of a cut stump with Tordon RTU


A simple girdle, followed by squirting Tordon into the cut, will also kill Buckthorn or other weed trees.


Girdles can also be done with a few simple hatchet chops.


Trees with minimal wildlife value are eliminated from natural areas in autumn and winter by girdling and then treating the wound with Tordon.

A hop hornbeam, or ironwood tree that has been girdled and then treated with Tordon. These common trees shade the forest floor and prevent oak seedlings from getting established.

A hatchet-girdled tree trunk waiting for the Tordon spray


A tree loppers can be used to top smaller trees and honeysuckle shrubs


Honeysuckles can be a bear to cut


Be sure to give all lopper-cut stems the Tordon treatment.


A backpack sprayer works great for many noxious weeds


Hit Honeysuckle or other weeds in the summertime with Crossbow. Spray the vegetation until leaves are wet


Reed Canarygrass can be controlled with Select, which will kill any grass but wont hurt sedges or forbs (flowers).


Backpack sprayers can get to hard-to-reach locations


Mowing can suppress weeds and keep them from going to seed. This may eventually control biennial species.


Fire may be another non-chemical control agent for weeds, but is better at battling a woody shrub or tree invasion


A late fall or early spring woodland burn can kill seedling Buckthorn, Honeysuckle and other ilk.


Hop hornbeam saplings waiting to be killed at Lake Meyer so the forest there can regenerate young oak or sugar maple seedlings in their place.

South-facing slopes at Lake Meyer are dominated by picturesque old oaks and managed as oak savannah, one of the rarest habitats in the whole world, a holdover from prehistoric times.

A natural native habitat is a healthy habitat