Mosquito Control

During the summer, the Health Department places traps throughout the city to collect adult mosquitoes. Weekly testing helps track West Nile virus and detect the presence of other potential viruses, such as eastern equine encephalitis, LaCrosse encephalitis, and Jamestown Canyon viruses.

West Nile virus has been detected in mosquitoes in NYC every year since 1999. In 2025, mosquitoes in NYC tested positive for Jamestown Canyon virus for the first time.

The Health Department uses two methods of pesticide application:

• Aerial Larviciding: Helicopters drop low-risk larvicide over marshes and other large natural areas to kill young mosquitoes before they become adults. The City does not use helicopters to treat residential areas.
• Adulticide: Trucks spray this pesticide to kill adult mosquitoes. It is used when testing has shown a high risk to human health. Spraying occurs in the evening in residential areas and parks.

The Health Department provides advance notification before dropping larvicide and spraying adulticide.

The Health Department follows City, State and Federal laws when applying pesticides. We do not accept requests for pesticide application.

Mosquito control events completed in 2026 will be listed here when West Nile virus season resumes.

View completed events from previous years below.

• When used correctly, pesticides pose no significant health risks to people or their pets.
• No reported diseases in people or pets have been linked with the use of pesticides in West Nile virus control efforts since 1999.
• People who are sensitive to spray ingredients may get a rash or have short-term eye or throat irritation.
• If you have a stronger reaction to pesticides, call the NYC Poison Control Center at 212-POISONS (212-764-7667).
• To minimize pesticide exposure:
  • When possible, stay indoors during spraying. If you have asthma or other respiratory conditions, stay inside.
  • Set the air conditioner vent to the closed position or choose the recirculate function.
  • Outdoor equipment and toys that are exposed to the pesticides we use are not a significant health risk. There could be some residue for a short period of time. Although it is not necessary, you can wash the toys and equipment with soap and water.
  • Wash skin and clothing that have been exposed to pesticides with soap and water. Always wash your produce thoroughly with water before cooking or eating.