Invasive Trees Are Giving Mosquitoes a Boost in Baltimore and D.C.’s Low‑Income Neighborhoods

It’s a familiar summer scene in many Baltimore and Washington, D.C. blocks: kids playing in sprinklers, adults sipping iced tea on porches, and—unfortunately—buzzing mosquitoes hovering around every water‑filled container. A new study now suggests that one of the culprits may be the very trees shading those neighborhoods.

Scientists led by Sarah Rothman, a former post‑doc at the University of Maryland and now with the Cary Institute of Ecosystem Studies, examined leaf litter from the canopy trees that dominate low‑income districts. Those trees happen to be invasive, non‑native species that have taken hold in the urban fabric.

When the leaves fall into rain‑filled buckets, flower pots, or any other standing water, they release nutrients that mosquito larvae love. In the lab, larvae fed on water infused with this invasive‑plant litter survived at noticeably higher rates, grew faster and turned into adults sooner than their peers fed on water with native‑leaf litter.

One of the mosquito species even produced adults with longer wings—a handy proxy that researchers use for body size. Bigger mosquitoes tend to bite more often and can carry diseases more efficiently, meaning the invasive trees could be silently amplifying health risks.

“We’re seeing a clear link between the type of canopy cover in a neighborhood and the mosquito life‑history traits that matter for disease transmission,” Rothman explains. The findings, published in the Journal of Medical Entomology and vetted by editor Lisa Lock and reviewer Robert Egan, add a new layer to the conversation about urban green spaces.

The study’s take‑away is straightforward: swapping out invasive canopy trees for native varieties could help curb mosquito numbers and, by extension, reduce the chance of disease spread. It’s a low‑tech, nature‑based approach that dovetails neatly with broader efforts to improve environmental equity.

While the research zeroes in on Baltimore and D.C., the authors caution that more work is needed to confirm whether the pattern holds in other cities. Still, the message is clear—what we plant in our streets can echo far beyond aesthetics, shaping the tiny ecosystems that thrive right under our windows.