Be aware of Invasive Species

The month of May is officially Invasive Species Awareness Month in Illinois!

The goal of the month is to help every resident of the state find out what he or she can do to help stop the spread of invasive plants, animals, insects and disease.

So, where to start?

Well, here is some info on a few of the most problematic invasive species one is likely to run across in this area:

1. Garlic mustard. Leaves on first year rosettes are green, heart shaped, and 1-6 inches long (shown to the left). Foliage becomes more triangular and jagged-looking as the plant matures. The plant is low growing, most often found in woodlands, and smells like garlic when crushed. Garlic mustard is a biennial, meaning that it only lives two years: in the first year it only has leaves and builds its roots; in the second year it uses the energy in its roots to grow flowers and produce seeds – lots and lots of seeds. And those seeds germinate the next year and the cycle starts all over again. This plant is a problem because it crowds out native woodland plants like shooting stars and trillium. Garlic mustard has also been implicated in preventing young oaks from sprouting.

2. Buckthorn (Glossy and European). This tree (or shrub) has dark green, oval leaves about 1-2 inches across. European buckthorn branches have thorns at the tips and the inner bark is orange, so it is very obvious when cut. Glossy buckthorn (shown in photo to the right) is very similar but grows in areas that are more wet. Both varieties of the tree produce purple to black berries in the fall. The berries are eaten by birds which then disperse the seeds. Buckthorn starts to grow earlier in the spring than native trees and shrubs, and it stays green later into the fall than most other plants. The tree was brought to the US from Europe as an ornamental (decorative) shrub. And in some communities, Buckthorn are pruned into topiary sculptures and revered for the dense, thorny screen that they provide between neighbors. Well, in natural areas, buckthorn wreaks havoc by shading out other shrubs, young oaks and all of the typical woodland herbaceous plants. Soon, the only things growing are buckthorn and maybe some garlic mustard.

3. Honeysuckle (Tartarian and Amur). Tartarian has red flowers and amur has white blooms shown to the left). Both have ovate (almond-shaped) leaves, but the Tartarian’s leaves are blue-green and 1 1/2 to 2 1/2 inches long and the Amur has leaves that are dark green on the top and light green underneath. The shrubs are native to parts of Asia and were introduced to the US by way of a Russian Arboretum in the late 1890s. Despite warnings by the Morton Arboretum in 1924 that the plants were weedy, the US Department of Agriculture recommended planting them for erosion control and wildlife habitat until 1984. Their leaves are the first to emerge in the Spring, and like buckthorn, they shade out native shrubs, young trees and herbaceous plants.

4. Gypsy moths. The caterpillars emerge in the first part of May (when serviceberry starts to bloom), growing steadily as they feed on tree leaves. They feed at night, then hide in tree bark or the ground during the day to avoid being eaten by birds. Their presence is usually first noticed when one sees that the leaves on a tree look lacy (since the caterpillars don’t eat the leaf veins). If the infestation is limited to just a few trees, one can remove the caterpillars as they climb down the trees in the morning. Larger infestations require professional help from an arborist. The moths emerge in mid July. Females are white and do not fly, so are fairly easy to spot (one is shown to the right laying eggs). They lay masses of eggs that look like smears of peanut butter on tree branches and other surfaces. One can scrape the egg masses off when spotted, but be sure to scrape them into a container and destroy them. If they are scraped onto the ground, they may still hatch! The gypsy moth was brought over to the US from Europe, and it is a problem because infestations can completely defoliate trees. If defoliation happens several years in a row, the tree can be killed. Oaks – McHenry County’s signature native trees – are a favorite of the gypsy moth.

Now that you know more about the impacts of non-native species, how will you celebrate this month?

I have a few suggestions:
1. Pull garlic mustard at a local woodland.
2. Cut buckthorn and honeysuckle at a local natural area.
3. Plant native plants in your yard.
4. Inspect your trees for evidence of gypsy moths.

The important thing is to do what you can – everything helps!

Visit the website: www.invasive.org/illinois to learn more.