WASHINGTON, D.C. — President Donald Trump signed an executive order titled "Eliminating Disease-Carrying Pests and Restoring Enjoyment of the Great Outdoors" on Tuesday. The directive sets a goal to reduce Washington, D.C.'s invasive mosquito population by 90% by 2028.

The executive order calls for reducing Washington, D.C.'s tick population by 50%. It directs federal agencies to use nonchemical methods, including landscaping, drainage improvements, and innovative technology, to control pests.

The official record states that by 2028, the Asian tiger mosquito, Egyptian mosquito, and other invasive mosquito populations, as appropriate, should be reduced by 90 percent and the tick population by 50 percent, with further reductions as practicable. The administration stated that methods developed for this initiative could potentially be applied nationwide in the future.

D.C. Health has maintained year-round surveillance and control efforts, including mosquito trapping, standing water elimination, and public education, to reduce vector-borne illness risks prior to the executive order. In the Washington, D.C. area, Culex pipiens can transmit West Nile virus. Aedes aegypti can transmit dengue, Zika, and yellow fever if those viruses are introduced locally.

Megan Fritz, associate professor of entomology at the University of Maryland, said there is scientific backing for the targets. "There is some scientific evidence to support the target reduction of some of the species that were mentioned in President Trump’s order," she said.

Fritz explained the biological mechanism behind one potential control method. "Wolbachia is an intracellular bacterium that’s found in many insect species, but does not infect humans." The incompatible insect technique (IIT) involves transfecting mosquitoes with Wolbachia. In the incompatible insect technique, scientists give male mosquitoes a different strain of Wolbachia and release them into the wild, resulting in fewer viable eggs when they mate with females.

"In the case of some of these studies, millions of Wolbachia-infected males get released into areas that are equivalent to, say, the size of 200 American football fields throughout a mosquito season, like April through October," he said. She noted the ongoing nature of such interventions. "This is not like a one and done. This is something that’s a long-term, sustained release program."

Studies in Fresno and Miami required releasing millions of Wolbachia-infected male mosquitoes into areas equivalent to 200 American football fields over mosquito seasons (April–October) to achieve population suppression. Populations of Aedes aegypti and Aedes albopictus have been suppressed at the 90% target level on relatively short time scales using species-specific techniques. Reducing invasive mosquito species such as Aedes aegypti and Aedes albopictus should not disrupt the local food web or pose a risk to other wildlife or native mosquito species.

"When that population suppression happens, it also lowers the risk of disease transmission," Fritz said. Aedes aegypti and Culex pipiens were brought to the Americas on ships tied to the trade of enslaved people in the 1600s and 1700s. Aedes albopictus entered the United States in the late 1900s and became an invasive species.

Why It Matters

The events described span 12 years, from 2016 to 2028. In 2016, during his first term, Trump signed an executive order directing the EPA to review and revise regulations on pesticide use, which included a focus on nonchemical alternatives for pest control, laying groundwork for the current D.C. initiative. Donald Trump has previously supported the use of Wolbachia-based mosquito control methods, as evidenced by his administration's funding of research into the technology through the National Institutes of Health (NIH) in 2024.

In 2021, the Department of Health and Human Services allocated $12 million to support pilot programs using Wolbachia-based mosquito control in three U.S. cities, including Washington, D.C. indicating prior investment in similar strategies. The Department of Health and Human Services (HHS) had previously issued guidelines in 2023 recommending the use of Wolbachia-infected mosquitoes as a safe and effective method for reducing Aedes aegypti populations in urban areas. A 2022 study published in the journal 'Science' found that the use of Wolbachia-infected mosquitoes reduced Aedes aegypti populations by 90% in controlled environments over a six-month period, supporting the feasibility of the 90% reduction target in D.C. A 2025 report by the Environmental Protection Agency (EPA) noted that the use of nonchemical mosquito control methods, such as landscape modifications and biological controls, had reduced mosquito populations by 40% in selected urban areas over the past five years.

What's New

The populations of Aedes and Culex in Washington, D.C. are directly affected by the executive order, as the order aims to reduce these invasive mosquito species and tick populations. The relevant number for invasive mosquito populations in Washington, D.C. is a target reduction of 90 percent by 2028, while the tick population is targeted for a 50 percent reduction by the same year.

A 2025 report by the Environmental Protection Agency (EPA) noted that the use of nonchemical mosquito control methods, such as landscape modifications and biological controls, had reduced mosquito populations by 40% in selected urban areas over the past five years.