Virginia is dealing with two invasive moth species that cause serious damage to trees and shrubs: the spongy moth, which strips leaves from hardwood forests across much of the state, and the box tree moth, a newer arrival first detected in 2025 that targets boxwood plants. The spongy moth is the more widespread threat, but both species are under active state quarantine programs.
The Spongy Moth: Virginia’s Biggest Moth Problem
The spongy moth (formerly called the gypsy moth, officially renamed in 2022) was introduced to the United States from Europe in the late 1800s. Its caterpillars feed on hundreds of tree species but strongly prefer oaks, especially white oak and chestnut oak on ridgetops. In heavy outbreak years, caterpillars can completely strip the leaves from large swaths of forest. Repeated defoliation weakens trees and can eventually kill them.
Virginia maintains a quarantine program to prevent the moth from spreading into uninfested areas. The Virginia Department of Agriculture and Consumer Services surveys populations each year and adds new localities to the quarantine when numbers warrant it. The state also cooperates with the U.S. Forest Service to suppress populations, with priority given to residential neighborhoods, forested areas, and heavily used public recreation sites.
How to Identify Spongy Moths
The spongy moth looks different at each stage of its life cycle, and knowing what to look for at the right time of year is the key to catching an infestation early.
Egg Masses (July Through March)
Females lay tan, velvety egg masses that measure 1 to 3 inches long. The fuzzy texture comes from hair shed from the female’s body. You’ll find them on tree trunks and the undersides of branches, but also on houses, lawn furniture, grills, fencing, firewood, sheds, vehicles, trailers, and playground equipment. Egg masses persist from mid-July all the way through the following March, making them the easiest stage to spot and destroy.
Caterpillars (March Through Early Summer)
Eggs hatch in early spring when oak leaves start to emerge. In parts of Virginia, hatching can begin as early as mid-March. Young caterpillars are small, dark, and hairy. As they grow, they develop a distinctive pattern: four pairs of blue spots behind the head followed by six pairs of red spots running down the back, with yellow and black markings on the head. No other caterpillar in Virginia has this exact combination. Mature caterpillars reach 1.5 to 2.5 inches long.
Adults (Mid-Summer)
Adult moths emerge in mid-summer. Males are grayish-brown with darker wing markings and feathery antennae, with a wingspan of about 1.5 inches. Females are larger, light-colored with dark wavy wing markings and a wingspan around 2.5 inches. Despite having fully formed wings, female spongy moths cannot fly, which is one reason they lay eggs on portable objects like firewood and vehicles. That’s how the moth hitchhikes into new territory.
What Homeowners Can Do About Spongy Moths
The most effective thing you can do is destroy egg masses between mid-October and mid-March, before they hatch. You have two options: spray them with a horticultural oil labeled for spongy moth egg masses until the mass is thoroughly soaked, or scrape them off into a container of soapy water. If you scrape, be careful not to gouge the bark. Both methods are simple and require no special equipment beyond what you’d find at a garden center.
Once caterpillars hatch in spring, barrier bands on tree trunks can stop them from climbing back up after they fall or drift down on silk threads. Wrap duct tape or another nonporous material around the trunk and coat it with a sticky product like Tanglefoot or petroleum jelly. Never apply sticky material directly to the bark, as it can damage the tree.
For chemical control, a biological pesticide based on the bacterium Bacillus thuringiensis (called Bt) is the most common treatment. Timing matters: Bt needs to be applied in May when caterpillars are still under half an inch long. It becomes significantly less effective on larger, older caterpillars. Organic options like insecticidal soaps, horticultural oils, and spinosad also work but only kill caterpillars on direct contact and break down quickly.
State Aerial Treatment Programs
Virginia runs two types of aerial treatments against spongy moths in cooperation with the USDA Forest Service. The first uses a virus that specifically targets spongy moth caterpillars, applied by aircraft in late March or early April to coincide with caterpillar emergence. The second is a mating disruption program: planes release a synthetic version of the female moth’s scent in late May or early June, which confuses males and prevents them from finding mates. Both treatments are species-specific, meaning they don’t harm other insects. Participating localities determine their own level of involvement, and federal cost-share money may be available.
The Box Tree Moth: A New Arrival
The box tree moth is a separate invasive species first detected in Virginia during the summer of 2025. Unlike the spongy moth, which attacks forest trees, the box tree moth feeds exclusively on boxwood plants, which are widely grown in Virginia landscapes, gardens, and nurseries. It defoliates boxwood rapidly.
As of late 2025, the box tree moth has been confirmed in Clarke County, Frederick County, and the city of Winchester. Both the state and federal government have responded with quarantines. Nurseries and garden centers in quarantined areas can only ship boxwood plants interstate under a compliance agreement and with a state-issued certificate. Moving boxwood parts, cuttings, clippings, or debris out of quarantined areas is prohibited except for decorative purposes.
How to Report a Sighting
If you’re outside the current box tree moth quarantine area and suspect your boxwood has been infested, you can report it through the Virginia Invasive Species Reporting Tool online or by emailing ReportAPest@vdacs.virginia.gov. If you’re inside the quarantine zone (Clarke County, Frederick County, or Winchester), VDACS doesn’t need additional reports. Instead, contact your local Cooperative Extension office for treatment recommendations specific to your situation.
For spongy moth concerns, your local Extension office is also the best starting point. They can help you confirm identification, assess the severity of an infestation, and connect you with any local suppression programs your county may be participating in.