Ohio is dealing with two invasive moth species that are actively spreading across the state: the spongy moth, which has established populations in 51 of Ohio’s 88 counties, and the box tree moth, a newer arrival first detected in 2023 that already has quarantines in 14 counties. Both are causing real damage to trees and landscapes, and both are worth knowing how to identify.
The Spongy Moth: Ohio’s Biggest Moth Problem
The spongy moth (formerly known as the gypsy moth) is the more widespread of the two. Its caterpillars strip leaves from trees, and they’re not picky eaters. Oaks are their favorite, but they’ll feed on maple, apple, hickory, basswood, birch, willow, poplar, pine, spruce, hemlock, and more. When populations get dense enough, they’ll eat almost anything with leaves.
Currently 51 Ohio counties are under state and federal quarantine, meaning there are restrictions on moving outdoor items like firewood, nursery stock, and other materials that could carry egg masses to uninfested areas. The moth has been steadily expanding westward and southward across the state for decades.
How to Identify Spongy Moths at Each Life Stage
You’re most likely to notice spongy moths as egg masses or caterpillars, since the adults are short-lived.
Egg masses appear as tan, spongy lumps on tree trunks, branches, outdoor furniture, vehicles, or any sheltered surface. Each mass contains 100 to 600 eggs protected by a light, almost hairy covering. Fresh masses feel firm; older ones get softer. They’re roughly the size of a quarter or larger and easy to spot once you know what to look for.
Caterpillars hatch in spring and start out tiny, about a quarter inch long, dark brown to black, and very fuzzy. As they grow over roughly seven weeks, they develop a distinctive pattern: two rows of colored spots running down their backs, with five pairs of blue spots followed by six pairs of red. Fully grown caterpillars reach about two inches. Their hairs can cause skin irritation, so avoid handling them bare-handed.
Adult females are white with brown markings that form an inverted V pointing toward the head. Despite having wings, females are too heavy-bodied to fly. Males are smaller, brownish with black markings, and have a wingspan of about one inch. They fly in a distinctive zigzag pattern.
What Defoliation Does to Trees
When spongy moth caterpillars strip a tree’s leaves, the tree has to spend stored energy regrowing them. Deciduous trees (oaks, maples, and others that drop leaves in fall) can usually regrow a full set by midsummer, and most healthy trees survive two or three consecutive years of defoliation without dying. But each round of leaf loss weakens the tree, making it more vulnerable to disease and other insect problems. If a drought, fungal infection, or secondary pest hits during the same period, trees can die.
Evergreens are a different story. Pines, spruces, and hemlocks don’t regenerate foliage as readily, and a single complete defoliation can kill them. Caterpillars usually turn to conifers only when preferred deciduous trees are scarce or populations are especially high.
The economic effects extend beyond individual trees. Severe outbreaks can reduce maple syrup production and damage the value of residential and commercial landscapes.
The Box Tree Moth: A Newer Threat
First detected in Ohio in June 2023 near the border of Hamilton and Clermont counties, the box tree moth is an invasive species from East Asia that feeds exclusively on boxwood. That narrow diet makes it a serious concern for Ohio’s horticulture industry, since boxwood is one of the most widely planted ornamental shrubs in the state.
The infestation has spread quickly. As of January 2026, 14 Ohio counties are under quarantine: Hamilton, Clermont, Butler, Warren, Montgomery, Miami, Greene, Preble, Clark, Cuyahoga, Ashtabula, Lorain, Lake, and Lucas. The quarantine expanded after new detections between May and October of the previous year.
Box tree moth caterpillars are green and yellow with white, yellow, and black stripes and black spots. Adults are nocturnal, with white, slightly iridescent wings bordered by an irregular thick brown band. Signs of infestation on your boxwood include chewed or missing leaves, yellowing or browning foliage, white webbing in the branches, and green-black droppings on or around the plant.
What You Can Do About Spongy Moths
The most effective thing homeowners can do is destroy egg masses before they hatch in spring. The best window for this is after the first hard frost in fall through late winter, when temperatures are above about 40°F. Waiting until after the first hard frost is important because a tiny parasitic wasp that naturally attacks spongy moth eggs needs time to build up its numbers during late summer and early fall. Scraping masses too early removes eggs that those wasps would have parasitized.
To remove egg masses, scrape them off surfaces into a container of soapy water and let them soak for two full days before discarding in the trash. Don’t just knock them to the ground or try to crush them in place. Many eggs will survive and hatch the following spring. Any portion of the mass you can’t fully scrape off may also contain viable eggs, so be thorough.
Check tree trunks, branches, the undersides of outdoor furniture, wheel wells of vehicles, firewood stacks, and any sheltered crevice. If you’re in a quarantined county, avoid moving firewood or outdoor items to non-quarantined areas.
Reporting a Sighting
If you spot either moth outside a quarantined area, the Ohio Department of Agriculture wants to hear about it. The state runs an online tool called the Ohio Plant Pest Reporter where you can submit sightings directly. Take a clear photo before reporting, as ODA staff cannot identify the pest without one. These citizen reports help the state prioritize survey areas and track how infestations are spreading.