Tennessee’s forests and landscapes face serious threats from non-native insects that arrived without natural predators to keep their populations in check. These invasive species cause millions of dollars in damage annually to trees, crops, and ecosystems across the state.
From the emerald ash borer decimating ash tree populations to fire ants creating painful hazards in yards, you need to recognize these destructive insects to protect your property and contribute to statewide monitoring efforts.
Understanding what these nine species look like, where they’re found, and how they spread helps you take action before infestations spiral out of control.
1. Emerald Ash Borer
The emerald ash borer (Agrilus planipennis) stands as one of Tennessee’s most devastating tree killers since its detection in the state. This metallic green beetle measures about half an inch long and targets all native ash species with ruthless efficiency.
Adult beetles feed on ash tree foliage, causing minimal visible damage, but their larvae tunnel beneath the bark and disrupt the tree’s ability to transport water and nutrients. Infested trees show distinctive signs including crown dieback, D-shaped exit holes in the bark, and increased woodpecker activity as birds seek out the protein-rich larvae. The serpentine galleries created by feeding larvae eventually girdle the tree, cutting off its life support systems.
Tennessee officials have implemented quarantines on moving ash wood products to slow the beetle’s spread, though the insect has already established populations across multiple counties. Trees typically die within two to four years of initial infestation.
Property owners with valuable ash trees can explore treatment options including systemic insecticides, though prevention through early detection remains the most cost-effective approach. The loss of ash trees affects not just aesthetics but also wildlife habitat and forest ecosystem functions.
Pro Tip: Check ash trees in late spring and early summer when adult beetles are most active. Look for D-shaped exit holes about one-eighth inch in diameter—these are telltale signs of emerald ash borer presence.
2. Hemlock Woolly Adelgid
The hemlock woolly adelgid (Adelges tsugae) appears as tiny, aphid-like insects covered in distinctive white, cotton-like wax that protects their colonies at the base of hemlock needles. This invasive pest from East Asia feeds by sucking sap from young hemlock twigs, which prevents new growth and causes needles to turn grayish-green before dropping prematurely.
Eastern hemlock and Carolina hemlock trees suffer the most severe damage, with infested trees typically dying within a few years as they lose the ability to photosynthesize and transport nutrients. The ecological consequences extend far beyond individual trees—hemlocks provide critical stream temperature regulation, prevent erosion along stream banks, and offer essential habitat for numerous wildlife species.
Key Insight: Hemlock woolly adelgid spreads primarily through storm winds, migratory birds, and hitchhiking on mammals and humans. Infested nursery stock also introduces the pest to new areas, making it crucial to inspect plants before purchasing.
Tennessee forests have already experienced significant hemlock mortality from this invasive species. Management strategies include releasing predatory beetles that feed on adelgids and applying horticultural oils or systemic insecticides to valuable specimen trees. The woolly masses become most visible in late fall through early spring, making this the optimal time for detection and treatment planning.
3. Spongy Moth
The spongy moth (Lymantria dispar), formerly known as gypsy moth, ranks among the most destructive invasive forest pests in North America, having defoliated over 92 million acres since its introduction in the late 1800s. The caterpillars are easily identified by their distinctive red and blue dots running along their backs.
These voracious eaters show a strong preference for oak leaves but will consume foliage from over 300 different tree and shrub species when populations explode. A single caterpillar can consume up to one square foot of foliage, and during outbreak years, forests can be completely stripped of leaves by early summer. The stress from repeated defoliation leaves trees vulnerable to other pests, diseases, and environmental stressors.
Female moths cannot fly, which limits natural spread, but egg masses often hitchhike on vehicles, firewood, and outdoor equipment. Each tan, fuzzy egg mass contains 500 to 1,000 eggs and can be found on tree bark, buildings, outdoor furniture, and vehicles. Tennessee residents should inspect these items regularly, especially when moving between counties or states.
Management approaches include manually destroying egg masses in winter, applying bacterial insecticides like Bacillus thuringiensis during early larval stages, and setting pheromone traps to monitor population levels. The caterpillars emerge in spring, typically around late April or early May, making this the critical window for intervention.
4. Brown Marmorated Stink Bug
The brown marmorated stink bug (Halyomorpha halys) has become a common agricultural and household nuisance across Tennessee since its introduction from Asia. This shield-shaped insect measures about three-quarters of an inch long with distinctive alternating light and dark bands on its antennae and a white or pale pattern along the edges of its abdomen.
These pests feed on a remarkably wide range of fruits, vegetables, and crops including apples, peaches, soybeans, tomatoes, and sweet corn. Their feeding causes dimpling, scarring, and internal damage that makes produce unmarketable. Agricultural losses in the mid-Atlantic region alone have reached millions of dollars during peak infestation years.
Beyond crop damage, brown marmorated stink bugs seek shelter inside buildings during fall months, congregating in attics, walls, and other protected spaces to overwinter. While they don’t reproduce indoors or cause structural damage, they release their characteristic foul odor when disturbed or crushed, making them particularly unwelcome houseguests.
Common Mistake: Using traditional insecticides often proves ineffective against stink bugs due to their hard exoskeleton and the timing of application. Physical removal methods like vacuuming combined with sealing entry points work better for home infestations.
Control strategies focus on exclusion—sealing cracks around windows, doors, and foundations before fall. For gardens and orchards, repeated applications of targeted insecticides during active feeding periods provide some relief, though complete control remains challenging. Row covers can protect high-value crops during peak activity periods.
5. Japanese Beetle
The Japanese beetle (Popillia japonica) brings a double threat to Tennessee landscapes through both adult and larval feeding damage. Adult beetles display metallic green bodies with copper-colored wing covers and measure about half an inch long. Small white tufts of hair along their sides distinguish them from similar-looking native beetles.
These insects emerged as significant pests after their accidental introduction to the eastern United States in the early 1900s. Adults feed on over 300 plant species, skeletonizing leaves by consuming tissue between the veins and leaving behind a lace-like appearance. They show particular fondness for roses, grapes, linden trees, and various ornamental plants. The grubs, or larvae, live in soil and feed on grass roots, creating brown patches in lawns and making turf easy to roll back like carpet.
The beetles follow a predictable annual cycle, with adults emerging from soil in late June and remaining active through August. They feed and mate throughout this period, with females returning to soil to lay eggs that hatch into the destructive grubs. These C-shaped white larvae remain in the soil over winter, resume feeding in spring, and pupate in early summer to complete their life cycle.
Management requires a two-pronged approach addressing both life stages. For adults, handpicking in early morning when beetles are sluggish provides effective control for small infestations. Neem oil and pyrethrin-based sprays offer organic options, though they require repeated applications. For grubs, beneficial nematodes applied to soil in late summer target larvae before they cause extensive root damage. Milky spore disease provides long-term biological control in lawns, though it takes several years to establish fully.
6. Kudzu Bug
The kudzu bug (Megacopta cribraria) arrived in Tennessee as an unintended consequence of widespread kudzu vine infestations. This olive-green to brown insect resembles a small beetle or stink bug, measuring about one-quarter inch long with a rounded, box-like shape covered in tiny pits.
Initially appearing in Georgia in 2009, the kudzu bug spread rapidly throughout the Southeast and reached Tennessee shortly thereafter. While these bugs feed primarily on kudzu—which some viewed as a potential benefit—they also attack soybeans, wisteria, and other legume crops, causing significant agricultural losses. Their feeding on soybean plants reduces yields through stunted growth, deformed pods, and reduced seed quality.
The bugs gather in large numbers on light-colored surfaces of homes and buildings during fall as they seek overwintering sites. Like stink bugs, they produce a foul-smelling defensive secretion when threatened or crushed. This secretion can stain surfaces and cause skin irritation in some people, adding a nuisance factor beyond their agricultural impact.
Important Note: Never crush kudzu bugs against your skin, as their defensive secretion can cause burning sensations and temporary redness. Use gloves or vacuum them up instead.
For homeowners, preventing entry through caulking and weather stripping protects against indoor invasions. In agricultural settings, scouting fields during early growth stages allows for targeted insecticide applications when populations reach economic thresholds. Natural predators are beginning to exploit this food source, potentially providing biological control as ecosystems adapt.
7. Red Imported Fire Ant
The red imported fire ant (Solenopsis invicta) creates both health hazards and ecological disruption across Tennessee’s landscapes. These reddish-brown ants measure between one-eighth and one-quarter inch long and build distinctive dome-shaped mounds in open, sunny areas including lawns, pastures, parks, and roadsides.
Native to South America, fire ants spread to Mobile, Alabama in the 1930s and have since colonized much of the southeastern United States. A single colony can contain 200,000 to 500,000 workers and multiple queens, allowing populations to grow explosively under favorable conditions.
The ants are highly aggressive when their mounds are disturbed, swarming and delivering painful, burning stings that produce characteristic white pustules within 24 hours.
Beyond their painful stings, fire ants displace native ant species and other ground-dwelling insects, disrupting ecosystem functions like seed dispersal and soil aeration. They damage crops by protecting plant-sucking insects like aphids in exchange for honeydew, and they chew on developing plant tissues.
Electrical equipment attracts fire ants for unknown reasons, leading to damage in air conditioning units, traffic signals, and farm equipment.
| Control Method | Effectiveness | Best Application Timing | Considerations |
|---|---|---|---|
| Individual mound treatment | High for single mounds | Any time mounds are active | Must treat all mounds in area |
| Broadcast bait | High for large areas | Spring and fall when ants are foraging | Requires proper weather conditions |
| Two-step method | Highest overall | Seasonal application | Combines broadcast bait with mound treatment |
| Boiling water | Moderate | Immediate response | Only kills ants it contacts; doesn’t eliminate queen |
The two-step control method combines broadcasting bait across the entire area followed by treating individual problem mounds with contact insecticides. This approach provides the most effective long-term control by eliminating colonies throughout the property while immediately addressing high-traffic areas.
8. Asian Longhorned Beetle
The Asian longhorned beetle (Anoplophora glabripennis) represents a federally quarantined wood-boring insect that poses severe threats to hardwood trees across North America. This striking black beetle with white spots measures one to one-and-a-half inches long and features distinctive long antennae banded in black and white that extend well beyond its body length.
Native to China and Korea, this beetle attacks healthy hardwood trees including maples, willows, elms, and birches. Females chew oval pits in bark to lay their eggs, and the resulting larvae tunnel through wood, creating extensive galleries that structurally weaken trees. Infested trees show round exit holes about three-eighths inch in diameter, sawdust-like material at the tree base, and oozing sap.
The damage progresses slowly but inevitably—trees typically die within three to five years of initial infestation as the larvae destroy the tree’s vascular system. The loss of street trees, park specimens, and forest stands would devastate communities aesthetically and economically, potentially costing billions in removal, replacement, and lost property values.
Key Insight: Asian longhorned beetles spread primarily through the movement of infested firewood, wood pallets, and solid wood packing materials. Never transport firewood long distances—buy local wood or purchase kiln-dried certified lumber.
Federal and state agencies maintain strict quarantines in areas where infestations are detected, often requiring the removal and destruction of host trees within a half-mile radius. Early detection through visual surveys during summer months when adults are active provides the best chance for successful eradication. Tennessee residents should report any suspected sightings immediately to state forestry officials.
9. European Paper Wasp
The European paper wasp (Polistes dominula) has successfully established populations throughout Tennessee since its introduction to North America. This slender wasp displays distinctive black and yellow markings with relatively little hair on its body, measuring about three-quarters of an inch long. The wasps construct umbrella-shaped paper nests under eaves, in attics, and within various protected spaces.
Unlike many invasive species, European paper wasps provide some benefits by hunting caterpillars and other insect pests to feed their larvae. However, they build nests in inconvenient locations around homes, outbuildings, and recreational areas, creating conflict with human activities. Their aggressive nest defense and painful stings make them problematic, especially in high-traffic areas.
These wasps outcompete native paper wasp species for nesting sites and food resources. Their ability to establish larger colonies and their willingness to reuse nest sites from year to year give them competitive advantages. They become most active during late summer and early fall when colony populations peak and workers forage intensely for protein and sugar sources.
Pro Tip: Inspect potential nesting sites in early spring when queens are just beginning nest construction. Removing small nests with just a few cells is much safer and easier than dealing with mature colonies containing dozens or hundreds of workers.
For nest removal, approach during cool morning hours when wasps are less active. Aerosol wasp sprays designed for distance application allow safe removal from several feet away. Always wear protective clothing and plan an escape route before attempting removal. For nests in difficult locations or if you’re allergic to stings, professional pest control services provide the safest option.
Prevention focuses on eliminating potential nesting sites by sealing gaps in siding, screening vents, and maintaining door sweeps. Removing nests in early spring before populations grow prevents larger problems later in the season. Unlike honeybees, paper wasps don’t reuse the same nest year after year, but they often build new nests in the same general area if conditions remain favorable.
Conclusion
The invasion of non-native insects continues to challenge Tennessee’s forests, agriculture, and residential landscapes. Each of these nine species demonstrates how quickly invasive pests can establish, spread, and cause extensive damage when introduced to new environments without natural controls.
Your role in monitoring and reporting these invasive insects directly supports statewide management efforts. Many infestations are first detected by vigilant residents who notice unusual insects or unexplained tree damage. Tennessee maintains reporting systems through the Protect Tennessee Forests website and the Department of Agriculture where you can submit photos and location information for suspected invasive species.
Prevention remains the most cost-effective strategy for managing invasive insects. Avoid transporting firewood between counties or states, inspect plants carefully before purchasing, and clean equipment when moving between properties. These simple practices reduce the accidental spread of destructive pests.
Early detection leads to better management outcomes. Regularly inspect trees on your property for signs of damage, monitor pest populations in gardens and landscapes, and familiarize yourself with the distinctive features of these nine species. The faster an infestation is identified and reported, the greater the chance of containing it before widespread damage occurs.
Tennessee’s natural resources—its forests, agricultural lands, and diverse ecosystems—face ongoing threats from invasive species. By staying informed about these nine harmful insects, recognizing their signs, and reporting sightings to appropriate authorities, you contribute to protecting the state’s environmental and economic health for future generations.
