Non-Native Invasive Insects / Animals
Insects play a valuable role in natural communities. They provide food to birds and other animals, and they help break down organic matter. But non-native insects can devastate entire natural communities.
Chances are good that the insects that have successfully hitched rides around the world to reach other continents and become big problems are pretty robust. But it's not guaranteed that in their home continent they have a reputation as a pest. Why? Ecobit: The Making of a Pest
(Tip: To explore the stewardship challenges of pests in a particular park, find a park of interest in Parks & Places. Then look for that park's Stewardship & Ecological Threats section.)
Explore this page:
- Insect Pests
- You Can Make a Difference!
Gypsy moth defoliation and mortality can create extensive sunlit openings in the forest canopy, allowing understory trees such as red maple to grow.2 In combination with over-browsing of oak seedlings by deer and the presence of non-native invasive plants, large opening such as these can result in a complete shift in forest canopy composition.
Gypsy moth caterpillars are hairy and have distinctive markings: five pairs of blue dots on the back near the head, followed by six pairs of red dots.3 They do not build webs, as do the native eastern tent caterpillar and fall webworm, which rarely kill trees.4
Native to Europe and Asia, the gypsy moth became established in America in the late 1800s, and reached the mid-Atlantic region a century later.
Emerald Ash Borer
The emerald ash borer (Agrilus planipennis) could be as devastating to ash trees in the U.S. as the chestnut blight was to American chestnut a century ago.
This half-inch long, Asian metallic green beetle is a relative newcomer to America. First found in 2002 in Michigan, the emerald ash borer spread among ash trees quickly, often hitching rides on infested firewood and nursery stock. By 2009, it had reached twelve states including Virginia and Maryland, and two Canadian provinces, killing hundreds of millions of trees.
As they feed, emerald ash borer larvae make S-shaped tunnels just under the bark of ash trees, destroying the trees’ circulatory system, or cambium. Emerging adults make D-shaped exit holes in the bark (flat on top, rounded on the bottom). Trees typically die within two years.5
Researchers are working to identify and develop biological control agents for emerald ash borer.
Asian Long-Horned Beetle
The Asian long-horned beetle (Anoplophora glabripennis) is a large and extremely destructive beetle that was probably imported from East Asia in wooden packing material in the 1990s.
Host trees include maple, box-elder, elm, birch, American sycamore, and willow. The Asian long-horned beetle’s larvae tunnel through the tree’s vascular system and heartwood, eventually killing it.
The white-spotted, glossy black bodies of these winged adult beetles are ¾–1 ½ inches long. Their black-and-white banded antennae are up to 4 inches long! They should not be confused with the duller whitespotted sawyer which attacks conifers.
Infested trees must be cut down (after the first frost kills adult beetles) and chipped or burned to prevent spread. Early detection is crucial for beating the Asian long-horned beetle. You can help; visit the website beetlebusters.info to get started.
Viburnum Leaf Beetle
This Eurasian beetle arrived in the United States in the early 1990s. By 2008, it had been documented in New England, New York, New Jersey, Pennsylvania, Ohio, Michigan as well as Ontario and the Canadian Maritime Provinces.
Cornell University has set up a citizen science project to help track the spread of this beetle.10
The adult is a tiny brown adult beetle the size of a matchstick head. It lays eggs in imperfect rows of chewed holes underneath younger twigs in summer and until the first frost.
The most effective control of this pest is to prune and destroy egg-infested twigs from late fall to early spring. Beneficial insects like ladybug larvae and adults and even certain stinkbugs feed on the viburnum leaf beetle or its larvae.
The sirex woodwasp (Sirex noctilio) is a pest of pine trees and other conifers. It arrives in the United States in pallets of wood from infested trees.
By 2014, sirex woodwasp had been found in New York and Pennsylvania, and scattered areas in Michigan, Connecticut, New Jersey, and Vermont. The first woodwasp was found in Indiana in 2002. It is considered a particular threat to plantations of pines in the southeastern United States.
When laying their eggs, female sirex woodwasps inject a fungus and irritating mucus into weakened or stressed pine trees. The fungus feeds their larvae, and further weakens the tree. In other countries where it is an invasive pest, the woodwasp often attacks loblolly trees on pine plantations.
Symptoms include a lightening or yellowing of the tree crown (sometimes reddish-brown), beads or streams of resin dripping from tiny holes in the bark, larvae tunnel in the wood, and exit holes.12
You Can Make a Difference!
"An ounce of prevention is worth a pound of cure." The sooner someone notices telltale signs of an insect invasion and speaks up, the better chance there is of controlling it. Whether it's in your own neighborhood or in a park, resource managers need your set of eyes to help keep a vigilant watch for these insect pests!
- 1. . 2003. Gypsy moth in North America.
- 2. . 1998. The red maple paradox: what explains the widespread expansion of red maple in eastern forests? BioScience. 48:355-364
- 3. . 2008. Focus on Plant Problems: Gypsy Moth.
- 4. . 2007. Eastern tent caterpillar. accessed March 3, 2009
- 5. . 2008. Emerald ash borer.
- 6. . 2017. Asian longhorned beetle.
- 7. . 2008. Asian longhorned beetle - Anoplophora glabripennis.
- 8. . 2017. Asian longhorned beetle.
- 9. Citekey 408 not found
- 10. . 2016. Viburnum Leaf Beetle.
- 11. . 2016. Viburnum Leaf Beetle.
- 12. . 2008. Proposed Program for the Control of the Woodwasp Sirex noctilio F. (Hymenoptera: Siricidae) in the Northeastern United States.
- 13. . 2016. Viburnum Leaf Beetle.
- 14. . 2014. Asian longhorned beetle.