Exotic Terrestrial Invertebrates in Illinois

Unless otherwise noted, photos © Illinois Department of Natural Resources. No photographs included within this information may be used on the internet, publications, or any other form of media without the photographer's express permission. All rights reserved.

emerald ash borer (Agrilus planipennis) photo © U.S. Department of Agriculture, Forest Service

The emerald ash borer is a native of Asia. It was discovered in Michigan in 2002 and spread quickly to other states and Canadian provinces. By 2006, it was present in Illinois. The larvae of this insect feed only on the inner bark of ash trees causing them to die. Millions of ash trees have been killed. This pest has caused tremendous costs to cities, homeowners, forestry product businesses and plant nursery owners.

honey bee (Apis mellifera)

The honey bee is dark brown on the head and thorax with alternating red-brown and black bands on the abdomen. Four, clear wings are attached to the thorax. The body is covered with small hairs, including on the eyes. There are three distinct forms of the honey bee: the queen (fertile female) is about three-fourths inch long; the worker (sterile female) is about one-half inch in length; and the drone (male) is about five-eighths inch long.

The honey bee may be found statewide in Illinois. It feeds on the nectar and pollen of flowers. It is a very important crop pollinator. Honey bees were brought to North America by early European settlers. These social insects nest in human-made hives, although they occasionally will leave the hive and form a nest in a hollow tree or similar object. Unlike most other social insects, the colony does overwinter in the hive in a large mass. The colony has three castes, or divisions: workers (sterile females), drones (males) and the queen (fertile female). Honey bees communicate through “dancing.” Special movements a worker makes inform the other members of the hive how far away and in what direction a good source of nectar may be found. The odor carried by the same bee will indicate the type of flower that it is found on. The worker bees spend the first part of their life doing chores in the hive, including constructing the waxy combs, caring for the eggs and larvae and tending to the queen’s needs. The last part of their lives is spent gathering pollen and nectar.  They exist only a few days in this foraging state before dying. A worker bee can sting but will die if it does so. The stinger is barbed and becomes anchored in the organism that is stung. As the bee pulls away, it leaves behind a section of its abdomen with the stinger.

Japanese beetle (Popillia japonica)
Native to Japan, it is believed that Japanese beetle larvae arrived in the United States in a shipment of iris bulbs. Adult beetles were first seen in New Jersey in 1916. The species has spread throughout much of the eastern half of the United States. More than 250 species of plants are eaten by Japanese beetles, and large infestations of beetles can be very destructive to plants.

nightcrawler (Lumbricus terrestris)

The nightcrawler, or dew worm, has a large body compared to other earthworms. It may attain a length of three and one-half to 12 inches. Like all earthworms, it has light- and touch-sensitive structures. Bristles on the underside of the body help it to move. It breathes through the skin. The skin is coated with mucus, which aids in its ability to breathe. Segments are present all along the body. A raised bump or ring, called the clitellum, secretes mucus to form the cocoon that covers the eggs and sperm as they are deposited outside the body. Small earthworms hatch from the cocoon. This worm may live four to eight years but is often preyed upon or dies before that time.

The nightcrawler may be found statewide in Illinois, It eats plant material at the soil’s surface. Its cast off wastes and debris are mixed at the soil’s surface with fresh plant material to form a small mound at the entrance of its burrow. The mound is called a midden. This species requires sexual mating for reproduction. The nightcrawler is native to Europe. It has spread from its native range through a variety of transport methods. Recent research has shown that it has a negative impact on native forests.

southern worm (Aporrectodea trapezoides)

The southern worm is small in size. Because it has no pigment, it has a gray appearance. This earthworm does not require mating for reproduction. Like all earthworms, it has light- and touch-sensitive structures. Bristles on the underside of the body help it to move. It breathes through the skin. The skin is coated with mucus, which aids in its ability to breathe. Segments are present all along the body. A raised bump or ring, called the clitellum, secretes mucus to form the cocoon that covers the eggs and sperm as they are deposited outside the body. Small earthworms hatch from the cocoon. This worm may live four to eight years but is often preyed upon or dies before that time.

The southern worm may be found statewide in Illinois. It helps to keep soils aerated and fertilizes the soil with its wastes. It eats organic matter in soil like decaying leaves, roots and dead animals as well as living organisms like protozoans, bacteria and fungi. When soil becomes cold in the fall and winter, it moves downward to avoid freezing. This worm is a food source for many species including birds, snakes, moles, toads and insects. This species was brought to North America through a variety of means. Its effects on plant communities in Illinois have not been extensively studied and are not well understood.

woodland white worm (Octolasion tyrtaeum)

The woodland white worm, or blue worm, is a small earthworm that shows a blue color when it is full of soil. The posterior and anterior ends are lighter than the rest of the body. Like all earthworms, it has light- and touch-sensitive structures. Bristles on the underside of the body help it to move. It breathes through the skin. The skin is coated with mucus, which aids in its ability to breathe. Segments are present all along the body. A raised bump or ring, called the clitellum, secretes mucus to form the cocoon that covers the eggs and sperm as they are deposited outside the body. This species has an orange clitellum. Small earthworms hatch from the cocoon. This worm may live four to eight years but is often preyed upon or dies before that time.

The woodland white worm may be found statewide in Illinois in areas of wet soil. It reproduces without sexual mating. This worm helps to keep soils aerated and fertilizes the soil with its wastes. It eats organic matter in soil like decaying leaves, roots and dead animals as well as living organisms like protozoans, bacteria and fungi. When soil becomes cold in the fall and winter, it moves downward to avoid freezing. This species was brought to North America through a variety of means. Its effects on plant communities in Illinois have not been extensively studied and are not well understood.

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