Terrestrial Invasives

Land Invaders

Whether they arrived accidentally or people brought them intentionally, terrestrial invasives are having a big impact on DuPage County’s natural areas. The list below features a few of the more prevalent species.

Asian Long-Horned Beetle Anoplophora glabripennis

Where It's From & How It Got Here

China accidentally in untreated shipping pallets

What It Looks Like

1 to 1.5 inches long; shiny black body with white-spotted wings; antennae longer than body with black and white bands; identical to native white-spotted pine sawyer beetle  and cottonwood borer

What It Does

Asian long-horned beetles prefer trees in the maple family, especially box elders and Norway, red, silver and sugar maples, but will also infest birches, elms, horse chestnuts and willows. One adult female can chew 30 – 90 depressions in a tree, laying an egg under the bark in each. The eggs hatch into caterpillarlike larvae, which feed on the tree’s inner tissues that move food between the roots and leaves. They eventually bore into the center of the tree, where they spend winter eating and growing. In summer they emerge as adults, each creating a dime-sized hole as it exits the tree. Yearly attacks of boring and feeding can fatally weaken trees or leave them vulnerable to other insects or diseases.

 

Emerald Ash Borer Agrilus planipennis

Where It's From & How It Got Here

Eurasia accidentally in shipping materials

What It Looks Like

0.5-inch-long green metallic body with a bronze underside;  sometimes confused with native six-spotted green tiger beetle

What It Does

This beetle has destroyed over 20 million ash trees since it arrived in the U.S. in 2002. The eggs hatch into white waxlike larvae that bore through an ash tree’s bark and feed extensively on the tree’s inner tissues, destroying the plant's ability to move food from its roots to its leaves. The larvae winter under the bark and emerge as adults in summer, creating D-shaped exit holes. Infested trees have thinning, yellowing crowns and branches that sprout from the bases along the trunks. Trees may also have increased woodpecker activity. Two to three years of infestations can kill a tree.

 

European Starling Sturnus vulgaris

Where It's From & How It Got Here

Europe to New York in 1890 by person wanting to bring all birds mentioned in William Shakespeare’s works to the U.S. 

What It Looks Like

Dark, iridescent robin-sized bird with light speckles

What It Does

Starlings swarm bird feeders and damage turf as they look for grubs. They're prolific, aggressive breeders that drive eastern bluebirds, northern flickers, red-bellied woodpeckers, wood ducks and other native birds from birdhouses and natural nests, destroying their eggs and young, too. Homeowners should check birdhouses regularly and remove starling nests immediately. (Because starlings are nonnative, they're not protected by laws that protect native birds' nests.)

 

Gypsy Moth Lymantria dispar

Where It's From & How It Got Here

Europe in 1868 by a scientist hoping to create silk-producing disease-resistant hybrid

What It Looks Like

Adult flightless females 1  inch long with cream-colored bodies and brown-speckled wings; males, which fly July – August, smaller with brown bodies, drab black-speckled wings and feathery antennae

What It Does

Females lay velvety tan masses containing up to 1,000 eggs in mid July under tree bark, often oaks. Caterpillars emerge in May and can reach 2 inches long. They're easily identified by six pairs of red dots and five pairs of blue dots along their backs. Hungry caterpillars can defoliate an entire tree before pupating into adults. Yearly attacks can fatally weaken trees or leave them vulnerable to other insects or diseases.

 

House Sparrow Passer domesticus

Where It's From & How It Got Here

Europe to New York in 1850s to control crop-damaging insects

What It Looks Like

Adults 5.75 inches long; males black bibs, white cheeks, chestnut mantles around gray crowns, chestnut-colored feathers on upper wings; females and young plain dingy-gray breasts; distinctive buff-colored eye streaks

What It Does

Large populations of house sparrows can carry diseases and spread them to household pets. They're aggressive breeders that drive tree swallows, eastern bluebirds, wrens and other native birds from birdhouses and natural nests, destroying their eggs and young, too. Homeowners should check birdhouses regularly and remove house sparrow nests immediately. (Because house sparrows are nonnative, they're not protected by laws that protect native birds' nests.)

 

Red-Eared Slider Celastrus orbiculatus

Where It's From & How It Got Here

Southern U.S. released as unwanted pets

What It Looks Like

Red marks behind ears

What It Does

Red-eared sliders raised in captivity and then illegally released into the wild can spread diseases to wild populations. Once in the wild, they also use food and habitat that would otherwide support native turtles.

 

Bird's Foot Trefoil Lotus corniculatus

Where It's From & How It Got Here

Eurasia

What It Looks Like

Bright yellow flowers often with fine red lines that develop into small pealike pods; five leaflets with central three held above the others; blooms late June – to fall 

What It Does

This perennial is often used — largely ineffectively — for soil and bank stabilization or as a groundcover crop. It easily escapes into roadsides and disturbed areas as well as meadows and prairies, where it forms dense mats, choking and shading out most other vegetation. Mowing can control it if used several times a year for several years.

 

Buckthorn Rhamnus spp.

Where It's From & How It Got Here

Eurasia to U.S. as an ornamental shrub

What It Looks Like

Oval or oblong dark green leaves; purple-black fruits; grows to 20 feet tall; common (R. cathartica) found in disturbed forests and abandoned fields and along roadsides, fencerows and the edges of prairies; glossy (R. frangula) found in wetlands, sedge meadows and mesic uplands

What It Does

Buckthorn grows and spreads quickly. Its berries act like a laxative so birds quickly spread its seeds. It's one of the first plants to leaf out in spring and one of the last to drop its leaves in fall. It creates low, dense canopies that block sunlight from native shrubs, young trees, wildflowers below, effectively smothering any native vegetation. Its roots are shallow, so gardeners can dig or pull small to medium-sized plants, especially when the soil is moist.

 

Crown Vetch Coronilla varia

Where It's From & How It Got Here

Eurasia to U.S. in 1950s to control erosion

What It Looks Like

Dark green leaves with 15 – 25 leaflets; pealike pinkish-white to deep pink flower clusters at the end of the stalks late spring – summer; narrow, pointed seed pods in 2- to 3-inch-long crown-like clusters; creeping 2- to 6-foot-long stems

What It Does

Crown vetch invades prairies and other natural areas, smothering native vegetation as it grows. It climbs over small trees and shrubs, forming large monocultures, and spreads by producing large amount of seeds and by rhizome growth. Mowing can control it if used several times a year for several years.

 

Garlic Mustard Alliaria petiolata

Where It's From & How It Got Here

Europe by early settlers as an edible and medicinal herb

What It Looks Like

Grows first year as a rosette — circular arrangements of leaves — close to the ground with scalloped, kidney-shaped green leaves; grows 2 – 3.5 feet tall with clusters of small four-petaled cross-shaped white flowers; seeds develop in erect, slender, four-sided pods beginning in May and are viable for up to 20 years

What It Does

Garlic mustard is found in disturbed shaded areas, woodlands and floodplains. The plant is “allelopathic,” which means it releases chemicals that suppress native plants, especially spring wildflowers. This affects not only the wildflowers but also the animals that depend on their foliage, pollen, nectar, fruits, seeds and roots.

To successfully control garlic mustard, gardeners must prevent plants from dropping seeds for several years until all viable seeds are exhausted. After the plants flower but before they set their seeds, gardeners should pull the plants or cut their stems at ground level and then remove the plants.

 

Honeysuckle Lonicera spp.

Where It's From & How It Got Here

Eurasia as ornamental shrubs

What It Looks Like

Red or orange berries; egg-shaped leaves; hollow stems grow from base in multistem clumps; grows to 10 feet

What It Does

Honeysuckles grow in woodlands, shrubby fields and disturbed areas and spread quickly by birds that eat their fruits and pass their seeds. They create low, dense canopies that block sunlight from native shrubs, young trees, wildflowers below, effectively smothering any native vegetation. Its roots are shallow, so gardeners can dig or pull small to medium-sized plants, especially when the soil is moist.

 

Oriental Bittersweet Celastrus orbiculatus

Where It's From & How It Got Here

Eastern Asia in 1860s as ornamental plant

What It Looks Like

Vine with rounded, finely toothed, alternate glossy leaves; white flowers bloom late May – mid-June; orange fruits; 12 feet tall on average but some growing on trees reach 60 feet tall

What It Does

This vine constricts trees and shrubs and eventually kills them by shading. Vines can be pulled out by the roots, preferably before fruiting. If fruits are present, vines should be bagged and either picked up with other landscaping waste or left in the bags and allowed to bake in the sun long enough to kill the seeds.

 

Teasel Dipsacus spp.

Where It's From & How It Got Here

Europe in 1700s as ornamental plants

What It Looks Like

Basal rosette — circular arrangement of leaves growing from base of stem — for at least a year then 6- to 7-foot stalks; prickly stems and leaves; purple flowers on common teasel (D. sylvestris), white on cut-leaved (D. laciniatus); plants die after flowering

What It Does

Teasel grows in heavily disturbed areas, prairies, savannas and sedge meadows and along roadways, where it's spread by mowers.

Gardeners can dig up rosettes but should remove as much of the root as possible to prevent resprouts. Cutting the plant with a sharp spade or shovel below the surface of the soil can be effective, but the area should be checked later for resprouts. Gardeners can carefully remove flower heads but should check later to ensure the plants have not produced new ones. Gardeners should avoid cutting flowering stalks before they are ready to drop their seeds because plants usually send up new stalks.