Ohio’s landscapes are under siege. Right now, eight invasive insect species are causing unprecedented damage across the state, destroying everything from backyard maple trees to commercial crop fields.
With spotted lanternfly sightings exceeding 3,000 reports monthly and emerald ash borer making a concerning comeback, Ohio residents need to know what they’re up against.
These aren’t your typical garden pests. Invasive bugs arrive without natural predators, reproduce rapidly, and can devastate entire ecosystems.
Some species can kill healthy trees within two years, while others threaten Ohio’s agricultural economy. The good news? Early identification and proper reporting can make all the difference in controlling their spread.
You’ll discover how to identify each species, understand the specific damage they cause, and learn exactly what to do if you spot them on your property.
Spotted Lanternfly
The spotted lanternfly (Lycorma delicatula) has become Ohio’s most rapidly expanding invasive threat. Since its first Ohio detection in 2020, this hitchhiking pest has spread to 17 states with monthly sightings exceeding 3,000 in Ohio alone.
Key Insight: Franklin County is among 12 Ohio counties currently under quarantine as this pest spreads rapidly across the state.
Physical Identification
Adult spotted lanternflies are unmistakable once you know what to look for. They measure about 1 inch long and ½ inch wide, with grayish wings featuring distinct black spots at the front and a speckled band at the rear. When they open their wings, you’ll see bright scarlet underwings with black spots and white-and-black bars. Their abdomen displays yellow coloring with black stripes.
The immature stages look completely different. Young nymphs start as small, black insects with white spots on their legs. As they mature, they develop red coloring with black spots before reaching their final adult form.
Host Plants and Damage
Spotted lanternflies aren’t picky eaters—they feed on over 100 different plant species, including economically important crops like grapes, hops, apples, and maple trees. When feeding, they excrete a sticky substance called honeydew that promotes sooty mold growth, further damaging plants and creating unsightly black coatings.
Pro Tip: Tree-of-heaven (Ailanthus altissima) is their preferred host plant. If you have this invasive tree on your property, monitor it closely for spotted lanternfly activity.
Egg Masses: The Hidden Threat
Between late September and early October, adult females lay 30-50 eggs in masses that look like gray, putty-like blobs. These egg masses can appear on any hard surface—tree trunks, outdoor furniture, vehicles, grills, and even building siding. Initially wet-looking and gray, they dry to resemble cracked mud or old chewing gum.
Important Note: Egg masses are how spotted lanternflies spread long distances. Always inspect outdoor equipment, vehicles, and firewood before traveling between counties.
What You Can Do
If you discover spotted lanternfly adults, nymphs, or egg masses, report them immediately to the Ohio Department of Agriculture. You can also use the Great Lakes Early Detection Network app to submit photos and location information.
For egg masses, scrape them off into a bag with rubbing alcohol. Adults can be stomped, but wear closed-toe shoes as they may jump toward you when threatened.
Emerald Ash Borer
Don’t let recent news fool you—emerald ash borer (Agrilus planipennis) isn’t disappearing from Ohio. After initial population crashes, this destructive beetle is experiencing concerning rebounds across southwest Ohio and other regions.
The Comeback Story
First detected in Ohio in 2003 near Toledo, emerald ash borer seemed to be under control after years of treatment programs and biological control releases. However, recent evidence suggests otherwise. Suspected feeding damage has reappeared on ash trees, woodpecker activity has intensified, and adult beetles are being photographed again in areas where they hadn’t been seen for years.
Common Mistake: Many property owners stopped treating their ash trees after not seeing emerald ash borer damage for several seasons. This treatment gap is contributing to population recovery.
Identifying the Beetle and Its Damage
Adult emerald ash borers are metallic green beetles about ½ inch long and 1/16 inch wide. They emerge from ash trees in May and June, leaving distinctive D-shaped exit holes about 1/8 inch in diameter.
The real damage comes from the larvae, which tunnel under the bark and feed on the tree’s phloem tissue. This creates serpentine galleries that disrupt nutrient and water flow. Look for these warning signs:
- Canopy thinning starting from the top
- D-shaped exit holes in the bark
- Vertical bark splits revealing galleries underneath
- Increased woodpecker activity (they feed on the larvae)
- Epicormic sprouting (new shoots growing from the trunk)
Timeline of Destruction
Emerald ash borer larvae can destroy ash trees within two to four years, but heavily infested trees may die in just one year. Unlike native borers that typically attack stressed trees, emerald ash borer kills healthy ash trees of all sizes.
Treatment and Management
The general rule for ash tree treatment is straightforward: if more than 30% of the canopy is dead or severely declining, the tree is unlikely to recover and should be removed for safety reasons.
For healthier trees, systemic insecticide treatments using imidacloprid or emamectin benzoate remain highly effective. Treatments must be applied before significant damage occurs and continued for the foreseeable future.
Pro Tip: Don’t transport ash firewood, even within Ohio. While the entire state is under quarantine, moving infested wood accelerates local spread.
Asian Longhorned Beetle
Asian longhorned beetle (Anoplophora glabripennis) represents one of Ohio’s most serious potential forest threats. Currently found in Clermont County under federal quarantine, this beetle could devastate Ohio’s hardwood forests if it spreads.
Why This Beetle Is Different
Unlike many invasive insects that prefer stressed trees, Asian longhorned beetle attacks healthy hardwoods including maples, elms, horse chestnuts, birches, and willows. The larvae bore through the wood itself, not just under the bark, creating structural damage that cannot heal.
Physical Characteristics
Adult Asian longhorned beetles are impossible to miss. These impressive insects range from ¾ to 1½ inches long, not including their long antennae. They’re shiny black with random white spots or blotches, and their antennae have alternating black and white segments. Their legs can be entirely black or partly blue.
Key Insight: Several native beetles are often confused with Asian longhorned beetle, but none have the specific combination of size, alternating black-and-white antennae, and random white spotting pattern.
Recognizing the Damage
Asian longhorned beetle damage is distinctive and devastating:
- Round exit holes about the diameter of a dime in trunks and branches
- Shallow, oval or round scars where adults chewed egg-laying sites
- Wood shavings (frass) at the base of trees or caught in branches
- Branch dieback and tree mortality in otherwise healthy-looking trees
Federal Response
The USDA Animal and Plant Health Inspection Service maintains strict quarantine regulations in affected areas. All host material within the quarantine zone must be chipped, burned, or otherwise destroyed to prevent spread.
Important Note: Moving any regulated materials out of quarantined areas requires federal permits and inspection. Violations carry significant penalties.
Hemlock Woolly Adelgid
Hemlock woolly adelgid (Adelges tsugae) continues expanding its range across Ohio, with confirmed infestations now in 21 counties. This tiny, aphid-like insect poses an existential threat to Ohio’s native eastern hemlock populations.
The White Woolly Warning Sign
Hemlock woolly adelgid adults are nearly microscopic at just 1.5 millimeters, but their white, woolly egg masses are easily spotted on the undersides of hemlock branches at the base of needles. These cotton-like clusters are most visible from November through May.
How They Kill Trees
Unlike many invasive insects, hemlock woolly adelgid feeds by inserting needle-like mouthparts directly into hemlock twigs and branches, extracting the tree’s stored starches. This feeding severely damages the tree’s ability to transport nutrients, causing needle drop, branch dieback, and eventual tree mortality within 4-10 years.
Beyond Individual Trees
The ecological implications extend far beyond individual hemlock trees. Eastern hemlocks create cool, moist understory environments that support unique communities of amphibians, birds, and other wildlife. Brook trout depend on the cool, shaded streams that hemlock forests provide during spawning season.
Detection and Reporting
Ohio Department of Natural Resources, Ohio Department of Agriculture, and Ohio State University Extension all coordinate hemlock woolly adelgid monitoring efforts. Use the Great Lakes Early Detection Network app to report suspected infestations with photos and precise location data.
Treatment Options
Chemical treatments using imidacloprid or dinotefuran can effectively control hemlock woolly adelgid on individual trees. Soil drenches, trunk injections, and foliar applications all have specific applications depending on tree size and proximity to water sources.
Common Mistake: Attempting to treat large forest stands with individual tree treatments is neither economical nor practical. Focus chemical control efforts on high-value ornamental trees or ecologically critical specimens.
Brown Marmorated Stink Bug
You might be surprised to learn that brown marmorated stink bug (Halyomorpha halys) is an invasive species. This pest is so common in Ohio that many residents assume it’s native, but it actually arrived from East Asia and has become a major agricultural and nuisance pest.
Agricultural Impact
Brown marmorated stink bug feeds on over 100 host plants, including economically important crops like soybeans, corn, tomatoes, peppers, and fruit trees. Their piercing-sucking mouthparts inject enzymes that break down plant tissues, causing wilting, dimpling, and crop quality losses.
In commercial agriculture, brown marmorated stink bug can cause significant economic damage. Soybean losses alone have reached millions of dollars in affected states, and Ohio’s diverse agricultural sector remains vulnerable.
Seasonal Behavior Patterns
Understanding their seasonal cycle helps with management timing:
- Spring emergence: Adults become active when temperatures consistently reach 70°F
- Summer reproduction: Multiple generations develop on host plants
- Fall aggregation: Adults seek overwintering sites in late September and October
- Winter survival: Large numbers enter homes, sheds, and other structures seeking warmth
The Stink Factor
True to their name, these bugs produce a foul-smelling chemical when disturbed or crushed. This defensive mechanism makes them particularly problematic when they invade homes in large numbers seeking winter shelter.
Pro Tip: Vacuum up indoor stink bugs rather than crushing them to avoid the smell. Dispose of the vacuum bag immediately or empty bagless containers outdoors.
Physical Identification
Adult brown marmorated stink bugs measure about ½ to ⅝ inch long and have the characteristic shield shape of all stink bugs. Their brown coloration includes darker bands on the antennae and alternating dark and light bands around the abdomen’s edge. Look for small white markings on the antennae and legs.
Management Strategies
Exclusion remains the most effective homeowner strategy. Seal cracks around windows, doors, and foundations before fall aggregation begins. Remove weeds and debris that provide alternate host plants near your home.
For agricultural situations, integrated pest management approaches combining cultural controls, beneficial insects, and targeted pesticide applications provide the best results.
Japanese Beetle
Japanese beetle (Popillia japonica) has been devastating Ohio lawns, gardens, and agricultural crops for decades. These voracious feeders attack over 300 plant species and can completely defoliate valuable ornamental plants in just a few days.
Dual-Phase Damage
Japanese beetles cause problems in both their adult and larval stages:
Adult beetles emerge in late June and July, feeding on leaves, flowers, and fruits. They skeletonize leaves by eating the tissue between veins, leaving behind a lacy appearance that severely weakens plants.
Grubs live in soil and feed on grassroots, causing brown patches in lawns that pull up easily like loose carpet. Heavy grub infestations can destroy entire lawn areas and attract wildlife that dig up turf searching for the protein-rich larvae.
Peak Activity Timing
Adult Japanese beetle activity peaks during Ohio’s hot summer months. They’re most active on warm, sunny days and tend to congregate in large numbers on preferred host plants. This aggregation behavior, driven by feeding and mating pheromones, can result in sudden, severe damage.
Preferred Host Plants
Japanese beetles show clear preferences among available plants:
Highly attractive plants: Roses, grape vines, linden trees, cherry trees, plum trees, and many vegetable crops including beans, corn, and okra.
Moderately attractive: Maple trees, birch trees, and various ornamental shrubs.
Resistant plants: Conifers, begonias, boxwood, and most native prairie plants.
Comprehensive Management Approach
Effective Japanese beetle management requires multiple strategies:
Biological controls include beneficial nematodes for grub control and predatory insects that attack adults.
Cultural practices like proper lawn maintenance, avoiding overwatering, and choosing resistant plant varieties reduce vulnerability.
Mechanical removal works for small populations—knock beetles into soapy water during cool morning hours when they’re less active.
Chemical controls should target timing to specific life stages for maximum effectiveness.
Important Note: Japanese beetle traps can actually increase damage by attracting beetles from surrounding areas. Use traps only as monitoring tools, placing them away from plants you want to protect.
Box Tree Moth
Box tree moth (Cydalima perspectalis) represents Ohio’s newest invasive threat, recently detected in Lapeer County by USDA. While still limited in distribution, this European and Asian native has the potential to devastate Ohio’s boxwood plantings.
Why Boxwood Matters
Boxwood shrubs are among the most popular landscape plants in Ohio, valued for their evergreen foliage, formal appearance, and versatility in landscape design. Many historic gardens and commercial landscapes depend heavily on boxwood for structure and year-round interest.
Larval Destruction Pattern
Box tree moth caterpillars feed primarily on boxwood leaves but can consume bark when foliage is depleted. Their feeding pattern is systematic and destructive:
- Initial feeding creates small holes in leaves
- Continued feeding results in complete defoliation
- Final stage larvae consume bark, girdling branches
- Girdled branches die, potentially killing entire shrubs
Identification Challenges and Solutions
Adult moths are white with brown borders on their wings and have a wingspan of about 1.5 inches. They’re active primarily at night, making detection difficult.
Larvae are green caterpillars with black heads, white stripes down their backs, and paired black dots along the white stripe. They can reach up to 1.5 inches in length when fully mature.
Webbing and frass provide the most reliable evidence of box tree moth presence. Look for silken webbing among boxwood branches and dark green pellets of frass beneath plants.
Early Detection Importance
Since box tree moth is newly established in the region, early detection and rapid response efforts could still prevent widespread establishment. Monitor boxwood plants regularly, especially during the growing season when larvae are most active.
Common Mistake: Assuming all caterpillars on boxwood are native species. Box tree moth larvae have distinctive markings and feeding patterns that differ from native pests.
Management and Treatment
European experience suggests that timely insecticide applications targeting young larvae provide the most effective control. Biological control agents are under investigation but not yet available in North America.
Viburnum Leaf Beetle
Viburnum leaf beetle (Pyrrhalta viburni) completes our list of Ohio’s most destructive invasive insects. This European native has systematically worked its way through Ohio’s native and ornamental viburnum populations, causing significant damage to both wild ecosystems and managed landscapes.
Host Specificity and Preferences
While viburnum leaf beetle attacks most Viburnum species, they show distinct preferences:
Highly susceptible: Arrowwood viburnum (V. dentatum), European cranberrybush (V. opulus), and American cranberrybush (V. trilobum)
Moderately susceptible: Nannyberry (V. lentago) and blackhaw (V. prunifolium)
More resistant: Koreanspice viburnum (V. carlesii) and doublefile viburnum (V. plicatum)
Life Cycle and Damage Timing
Understanding the viburnum leaf beetle’s life cycle helps predict damage timing:
Eggs overwinter in small holes chewed into viburnum twigs, covered with bark caps and excrement.
Larvae emerge in May and feed on leaves throughout spring and early summer, creating characteristic holes and eventually skeletonizing foliage.
Adults emerge in mid-summer and continue feeding on leaves while mating and laying eggs for next year’s generation.
Pro Tip: Examine viburnum twigs in winter for rows of small holes with bark caps—these indicate egg-laying sites and predict next season’s damage.
Economic and Ecological Impact
Viburnum species provide critical wildlife value, producing berries that feed over 35 bird species. Many viburnums also support native butterfly and moth larvae. Repeated defoliation by viburnum leaf beetle weakens plants, reduces berry production, and can kill shrubs within 2-3 years.
In commercial and residential landscapes, viburnum replacement costs can be substantial, particularly for mature specimen plants or formal hedge installations.
Integrated Management Strategies
Physical removal of egg masses during winter pruning reduces next season’s population. Look for the characteristic holes in twigs and remove affected branches.
Beneficial insects including parasitic wasps and predatory beetles can provide significant biological control when pesticides don’t disrupt them.
Plant selection favoring more resistant viburnum species helps reduce long-term management requirements.
Monitoring and early intervention prevents population buildups that overwhelm natural controls.
Chemical Control Considerations
If chemical control becomes necessary, target young larvae in late spring when they’re most vulnerable. Insecticidal soaps and horticultural oils can provide effective control with minimal environmental impact.
Important Note: Avoid broad-spectrum insecticides during viburnum flowering to protect pollinators that depend on these valuable nectar sources.
Taking Action: What Every Ohio Resident Can Do
Ohio’s invasive insect problems require community-wide action. Individual efforts, when multiplied across thousands of residents, create the early detection network essential for successful management.
Reporting Systems That Work
Ohio Department of Agriculture maintains the primary invasive species reporting system. Their Ohio Plant Pest Reporter provides the official channel for suspected invasive species discoveries.
Great Lakes Early Detection Network (GLEDN) offers a smartphone app that simplifies reporting with photo uploads, GPS location data, and expert verification.
Ohio State University Extension provides local expertise and can help with species identification questions.
Prevention Through Education
Understanding how invasive species spread empowers you to prevent new introductions:
- Inspect outdoor equipment before moving between locations
- Buy firewood locally instead of transporting it from other areas
- Clean vehicles and equipment when traveling from infested areas
- Choose native or non-invasive plants for landscaping projects
- Learn to identify high-risk species before they become established
The Economic Reality
Invasive species cost Ohio millions of dollars annually in damage to forests, agricultural crops, and urban landscapes. Early detection and rapid response programs represent the most cost-effective approach to minimizing these economic impacts.
Every confirmed early detection saves taxpayers money by enabling targeted management before species become widely established and expensive to control.
Creating Resilient Landscapes
As invasive species continue arriving in Ohio, creating resilient landscapes becomes increasingly important. Diverse plantings that include native species, proper plant placement, and integrated pest management practices help minimize vulnerability to new invasive threats.
Key Insight: The most sustainable long-term approach combines active monitoring, early intervention, and landscape diversification to reduce dependence on any single plant species.
Ohio’s battle against invasive insects requires vigilance, education, and coordinated action. By learning to identify these eight destructive species and participating in reporting networks, you become part of the solution. The earlier we detect new invasions, the better our chances of protecting Ohio’s valuable natural resources and economic interests.
Remember: your eyes are on the front lines of invasive species detection. What you notice and report could prevent the next ecological disaster.
