Spotted Lanternfly confirmed at multiple locations across the watershed
July 30, 2026
(Lycorma delicatula) have been confirmed at multiple locations across the watershed over the past two months — 28 iNaturalist observations from Watertown, Cambridge, Newton, Arlington, Brookline, and Waltham, with four logged in the past two days. These are presence records reflecting where observers have reported the species, not a measure of population size or density.
This planthopper, native to China and Southeast Asia, arrived in Pennsylvania in 2014 and has spread steadily north. Its preferred host is (Ailanthus altissima), itself an invasive that has colonized disturbed ground throughout this area — a ready-made food source. Adult lanternflies feed on the phloem of a wide range of trees, including maples, oaks, black walnut, and wild grape, depleting carbohydrate reserves and excreting a sticky honeydew that coats leaves and encourages sooty mold. If you spot one, report it on iNaturalist.
) are at peak abundance across the urban core — over a hundred sightings since late March, with adults now feeding heavily on oaks and maples in Williamsburg, Clinton Hill, Brooklyn Heights, and Lower Manhattan. The insects have spread from a focus point on Governors Island in late spring to establish themselves in clusters throughout Brooklyn and Manhattan within ninety days.
Their explosive presence here traces back to an earlier invasion.
(
Ailanthus altissima
), which arrived in these neighborhoods in the 1700s as an ornamental, proved to be the perfect host plant for this invasive pest. Now the lanternflies' honeydew coats street trees in a thin film of sticky residue that fuels
sooty mold blooms
— blackening foliage on the very maples and oaks that neighborhoods have spent years establishing and maintaining. The ecological cost compounds: weakened urban canopy, pest populations exploding where natural predators are scarce, and no easy way to manage the cycle without broad toxin applications.
