Spotted Lanternfly in Washington DC: The National Mall, the Metro, and a City-Wide Fight

Spotted lanternfly (Lycorma delicatula) has established itself across Washington DC. By 2026, confirmed populations span all 8 wards of the District — a milestone that reflects both the insect's aggressive spread and the particular geography of a dense, transit-connected urban core hemmed in by two of the most heavily infested states in the country (Maryland to the north and east, Virginia to the south and west).

DC is not merely a geographic passthrough. It is an infestation node in its own right — one with a unique mix of challenges that no other jurisdiction in the country shares: federal land management split between multiple agencies, a rapid transit system that mirrors the spread dynamics documented in New York City, and urban greenway corridors thick with tree of heaven that reach from the Maryland line to the Anacostia riverbank without a gap.

How SLF Arrived in DC — and How Quickly It Spread

Washington DC sits inside a ring of some of the earliest and heaviest SLF infestations in the United States. Montgomery County, Maryland (directly north of the District) and Arlington and Alexandria, Virginia (directly across the Potomac) both confirmed SLF populations by 2019 and 2020. With this level of infestation pressure on every border, DC's first confirmed detections were largely inevitable.

Initial reports came from the upper Northwest quadrant — neighborhoods closest to Montgomery County's already-established populations — before spreading southeast through the rest of the city. By 2025, DDOE (DC Department of Energy and Environment) and the Urban Forestry Division confirmed the insect's presence in all eight wards.

The mechanism of spread within DC is the same one that carried SLF across New York City's five boroughs: rapid transit. The Washington Metro rail network functions as an SLF highway. Adults land on train exteriors or hitchhike on commuters' clothing and bags, and egg masses deposited on rail infrastructure — metal beams, concrete supports, utility boxes — go unnoticed across the entire system. A single egg-mass-bearing commuter transferring between the Red, Green, and Blue lines at Metro Center or Gallery Place can seed populations in neighborhoods miles apart in a single trip.

Tree of Heaven: DC's Built-In SLF Infrastructure

Tree of heaven (Ailanthus altissima) is one of the most common trees in Washington DC, and its distribution in the city is not random. It dominates three specific landscape categories: alley edges, rail and highway rights-of-way, and roadside median strips — precisely the corridors that connect every neighborhood in the city.

DC's iconic alley network — over 1,500 alleys covering most of the city's blocks — is lined with mature tree of heaven that has never been systematically managed. These alleys form a continuous corridor system running through every ward, providing SLF with both breeding habitat and a protected travel route invisible from the streetscape. Along the Metro rail lines, tree of heaven grows in dense thickets along exposed above-ground segments in Northeast, Southeast, and Anacostia — unmanaged and uncontrolled, serving as permanent SLF source populations adjacent to the city's transit infrastructure.

What this means in practice: even if a DC resident successfully removes every tree of heaven from their own property, SLF populations in the surrounding alley network and rail corridors will continue to supply new infestations to their yard every season. Effective management in DC requires engagement at the neighborhood and corridor level, not just at the property line.

DC's Parks and Green Spaces at Risk

DC's green spaces cover a surprising fraction of the city's area — and most are now under SLF pressure.

Rock Creek Park is the District's largest natural area, running nearly the full length of the city from the Maryland line to the Potomac. Tree of heaven grows throughout the park's disturbed edges and creek margins. Rock Creek Park is managed jointly by the National Park Service and the DC Urban Forestry Division, and volunteer scraping events organized by NPS and local partners have begun targeting the park's TOH-heavy zones. If you want to take direct action, Rock Creek Park volunteer events are among the highest-leverage opportunities available to DC residents. Anacostia Park, stretching along the Anacostia River in the eastern half of the city, faces SLF pressure from both the tree of heaven stands along the river corridor and from heavy infestation in Prince George's County directly across the DC line. The park's riparian habitat makes broadcast pesticide applications inappropriate — trapping and scraping are the preferred tools here. Capitol Hill parks and the National Mall perimeter present DC's most complex management situation. The National Mall and most of the monumental core are under National Park Service jurisdiction, not DC government jurisdiction. This creates a coordination challenge: DDOE and the Urban Forestry Division manage SLF on DC-owned land, while NPS manages the same pest on federal parkland that can be a few feet away. The practical result is that management intensity and timing can differ across a single city block. NPS has its own SLF response protocols developed for federal parkland, but aligning those with DC's city-level program requires interagency communication that adds friction to an already demanding management problem.

Who Manages SLF in DC

DDOE (DC Department of Energy and Environment) leads the District's SLF response for DC-managed lands. DDOE works in partnership with the Urban Forestry Division of the DC Department of Transportation and with Casey Trees, DC's primary urban forestry nonprofit. Casey Trees has been active in public education on SLF identification and tree health assessment, and partners with DDOE on community outreach.

For DC government land and street trees, the Urban Forestry Division manages any SLF-related interventions on public trees. Residents can report concerns about SLF on street trees through the Urban Forestry portal.

For federal parkland — the National Mall, the monuments, Rock Creek Park's NPS-managed sections, and other NPS-controlled sites — the National Park Service's National Capital Region manages the response independently, coordinating with DDOE where boundaries intersect.

What DC Residents Should Do Now

Report

If you spot SLF in DC — at any life stage — report it through the DC urban forestry reporting portal at trees.dc.gov/pages/forest-health. Include your ward, the date, the life stage observed (egg mass, nymph, or adult), and a photo if you can.

You can also log sightings on iNaturalist tagged as Lycorma delicatula, which feeds into regional monitoring databases tracked by both DDOE and USDA APHIS.

Join the Fighter Network

The Lanternfly Watch fighter network connects DC residents with local action — reporting tools, volunteer events, and trap resources. Join the network here and add your sightings to the shared map so the community can see where SLF is active across the city in real time.

Volunteer at Rock Creek Park

Rock Creek Park volunteer scraping events are one of the most direct ways DC residents can reduce local SLF populations. NPS and local partners organize events through the fall egg-laying season. Watch for announcements through the Rock Creek Park NPS site and Casey Trees' event calendar.

Act on Your Property

Circle traps on tree of heaven and any high-traffic ornamental trees are your highest-impact tool during adult season (July–October)
Egg mass scraping from November through April — check every smooth surface on your property, including outdoor furniture, fences, and parked vehicles
Remove tree of heaven from your property if present — it is the primary reason SLF keeps returning
Dinotefuran trunk bands on high-value trees you want to protect during peak adult season

The Bigger Picture

DC's SLF problem is inseparable from the regional infestation. The District has no quarantine buffer — it is fully embedded in an already-infested landscape stretching from Pennsylvania through Maryland and Virginia. Management success in DC will depend on coordination with Maryland and Arlington/Virginia on corridor-level tree of heaven management, Metro system monitoring, and consistent public engagement across ward boundaries.

The complexity of federal-municipal coordination at sites like the National Mall is real, but it does not eliminate what individual DC residents can do. Reporting, scraping, trapping, and removing tree of heaven from private property remain the levers most directly in residents' control — and those actions, at scale, matter.

Key Sources

DC Department of Energy and Environment. Spotted Lanternfly Information. doee.dc.gov.
DC Urban Forestry Division. trees.dc.gov.
Casey Trees. caseytrees.org.
National Park Service, National Capital Region. nps.gov/subjects/invasives.
USDA APHIS. "Spotted Lanternfly." aphis.usda.gov.
Penn State Extension. "Spotted Lanternfly." extension.psu.edu/spotted-lanternfly.

Related: Spotted Lanternfly in Maryland · Spotted Lanternfly in Virginia · Interactive Infestation Map · How to Kill Spotted Lanternfly · Egg Mass Scraping Guide · Best Traps 2026