Types Of Invasive Pests Threatening Ohio Landscapes

Invasive pests–primarily insects and plant pathogens–have reshaped Ohio landscapes over the past several decades. They kill trees, reduce biodiversity, lower property values, and increase long-term management costs. This article describes the most significant invasive pests threatening Ohio, explains how to identify them and their impacts, and provides practical, actionable management strategies for homeowners, land managers, and landscapers.

Why invasive pests matter in Ohio

Invasive pests often arrive with no natural predators or controls, allowing populations to explode. Ohio’s mix of urban, suburban, and rural forests provides ample hosts for nonnative pests. Common consequences include:

• Tree mortality and replacement costs.
• Loss of canopy cover and ecosystem services.
• Increased pesticide use and associated non-target effects.
• Regulatory quarantines and restrictions on wood movement.

Understanding the major species and integrated responses helps protect individual properties and the broader landscape.

Major invasive insects and pathogens to watch in Ohio

The following sections highlight the most impactful invasive pests in Ohio. For each, I describe identification features, life cycle highlights relevant to control, damage symptoms, and recommended management steps.

Emerald ash borer (Agrilus planipennis)

Identification and signs

• Adults: metallic green beetles about 1/2 inch long.
• Damage: D-shaped exit holes in bark, S-shaped galleries under bark, thinning canopy, epicormic sprouting.

Life cycle and timing

• One generation per year in Ohio; adults emerge from late May through July.

Why it matters

• Kills ash trees of all sizes and ages. Tens of millions of ash trees have been lost in North America.

Management recommendations

• Monitor ash tree health yearly. Look for canopy thinning and bark splits.
• For high-value trees, use systemic insecticides (professional trunk injections or soil drenches) containing emamectin benzoate, dinotefuran, or imidacloprid on a recommended schedule. Emamectin benzoate is currently considered highly effective when applied by a certified arborist.
• Remove and properly dispose of heavily infested trees to prevent spread, following state and local regulations.
• Replace ash with diverse, non-ash species to reduce future risk.

Spotted lanternfly (Lycorma delicatula)

Identification and signs

• Adult: large, colorful planthopper with distinctive black spots on forewings and red hindwings (visible when flying).
• Nymphs: black and white spotted immature stages, later red-and-black instars.
• Damage: sap feeding leads to weeping wounds, honeydew accumulation, sooty mold, reduced vigor, and fruit/ornamental crop damage.

Life cycle and timing

• One generation per year. Adults appear in mid-summer and lay egg masses in fall on trees, stones, equipment, and vehicles.

Why it matters

• Highly mobile and readily spreads on transported materials. Causes economic damage to vineyards, orchards, and ornamentals.

Management recommendations

• Inspect and scrape off egg masses (use a putty knife into a container of alcohol or soapy water) in fall and winter.
• Use sticky bands cautiously on trunks to intercept crawlers; maintain bands to avoid trapping non-target species.
• Remove or manage preferred host trees such as tree-of-heaven (Ailanthus altissima), which supports spotted lanternfly populations; treating or removing tree-of-heaven reduces local pressure.
• Report sightings to authorities; early detection improves containment options.

Asian longhorned beetle (Anoplophora glabripennis)

Identification and signs

• Large longhorned beetle (1 to 1.5 inches) with distinctive long antennae banded in white and black spots on a glossy black body.
• Damage: perfectly round exit holes about 3/4 inch, sawdust-like frass, branch dieback, epicormic shoots.

Life cycle and timing

• Multiple-year development in wood before adult emergence.

Why it matters

• Attacks maples and many hardwood species. Known eradication programs elsewhere required tree removal and quarantines.

Management recommendations

• Early detection is critical. Inspect susceptible trees for exit holes and internal galleries.
• Do not move firewood or untreated wood products out of infested areas.
• If suspected, contact Ohio Department of Agriculture or local extension; do not attempt to treat with home remedies–eradication often requires coordinated removal and regulatory action.

Spongy moth (formerly gypsy moth) (Lymantria dispar dispar)

Identification and signs

• Caterpillars are hairy with blue and red dots; egg masses are buff-colored and fuzzy.
• Damage: severe defoliation of oaks and many hardwoods; repeated defoliation weakens trees and predisposes them to other pests and pathogens.

Life cycle and timing

• Egg masses overwinter; caterpillars feed in spring. One generation per year.

Why it matters

• Large outbreak cycles can cause widespread canopy loss and tree mortality.

Management recommendations

• Hand remove and destroy egg masses in fall and early spring.
• Apply Bacillus thuringiensis var. kurstaki (Btk) during early larval stages for effective biological control; timing is crucial–treat when young larvae are actively feeding.
• Mating disruption pheromones and biological agents (e.g., fungal pathogen Entomophaga maimaiga) are available in some programs.

Hemlock woolly adelgid (Adelges tsugae)

Identification and signs

• Tiny, sucking insect producing white woolly masses at the base of hemlock needles.
• Damage: needle loss, branch dieback, progressive tree decline and mortality.

Life cycle and timing

• Multiple generations per year; overwintering life stages persist on twigs.

Why it matters

• Hemlocks are foundation species in riparian and shaded forest habitats; loss changes microclimate and stream health.

Management recommendations

• Inspect hemlocks for white wool at the base of needles.
• For high-value trees, systemic insecticides (imidacloprid soil drench or trunk injections) and foliar treatments (dinotefuran) can protect trees; timing and dosages require professional guidance.
• Biological control agents (predatory beetles such as Laricobius nigrinus) have been used in restoration programs.

Japanese beetle (Popillia japonica)

Identification and signs

• Shiny metallic green beetle with copper-brown wing covers, about 1/2 inch long.
• Damage: Skeletonized leaves on roses, lindens, grapevines, and many ornamentals; grubs damage turf roots.

Life cycle and timing

• Adults active in summer; grubs in turf over winter.

Management recommendations

• Hand-pick beetles in early morning and drop into soapy water.
• Consider targeted foliar insecticides for severe defoliation, applied responsibly to avoid harming pollinators.
• Manage grubs with cultural practices: maintain healthy turf, aerify, and apply grub-targeted insecticides or biological controls (milky spore, beneficial nematodes) where appropriate.

Brown marmorated stink bug (Halyomorpha halys)

Identification and signs

• Shield-shaped stink bugs with marbled brown coloring; emit odor when disturbed.
• Damage: Feeding causes fruit scarring, deformation, and reduced marketability in apples, peaches, and vegetables.

Life cycle and timing

• Overwinters in buildings; adults emerge in spring and feed through summer and fall.

Management recommendations

• Seal buildings and windows to exclude overwintering adults.
• Use exclusion netting in high-value orchards and home gardens during fruiting.
• Rely on targeted insecticides only when thresholds are exceeded; indiscriminate spraying harms beneficial insects.

Integrated management principles for Ohio landscapes

Successful long-term protection relies on integrated pest management (IPM). Key principles:

• Monitor regularly: Early detection allows more options and reduces costs.
• Prioritize high-value and native species: Protect key canopy trees, specimen ornamentals, and rare species first.
• Use cultural controls: Diversify plantings, remove invasive host plants, maintain tree vigor through proper pruning, mulching, and watering.
• Apply biological controls where available: Support natural enemies and participate in community-level biocontrol releases when coordinated by agencies.
• Choose targeted chemical controls judiciously: Use systemic insecticides for soil- and wood-boring pests when warranted, applied by certified professionals to minimize non-target impacts.
• Adhere to quarantine and wood movement rules: Do not transport firewood, nursery stock, or untreated timber from known infested areas.

Monitoring, reporting, and community action

Early detection depends on informed residents and professionals. Practical steps:

• Inspect trees and shrubs at least twice per year–spring for defoliators and summer for borers.
• Learn common signs: exit holes, frass, waxy deposits, unusual dieback, and egg masses.
• Photograph and record GPS coordinates for suspected infestations, then report to state or county extension offices or the Ohio Department of Agriculture.
• Coordinate with neighbors and homeowner associations to organize surveys, removal of host plants, and shared treatment programs.

Practical takeaways for homeowners and land managers

• Prioritize inspection of ash, maple, hemlock, fruit trees, and oaks.
• Remove and properly dispose of infested or high-risk trees when necessary; do not store infested wood on-site.
• Hire certified arborists for treatments like trunk injections or when working near large trees.
• Use mechanical controls (egg scraping, hand-picking) and cultural practices (host removal, landscape diversity) before broad-spectrum insecticides.
• Keep records of treatments and tree health to track trends and justify long-term management investments.
• Participate in local outreach and reporting; community-level coordination amplifies individual actions.

Invasive pests remain one of the most consequential threats to Ohio landscapes, but informed, timely, and integrated actions can slow spread, reduce damage, and protect the ecological and economic value of trees and plants. Regular monitoring, diversified plantings, disciplined movement of wood and plants, and strategic use of chemical and biological controls are the core tools for keeping Ohio landscapes resilient.