News Release
August 26, 2014

City to Spray Insecticide Wednesday to Kill Mosquitoes

Targeted Effort Fights West Nile Virus in Dunning, Montclare, Belmont-Cragin and Austin



Ryan Gage,


Chicago - The Chicago Department of Public Health (CDPH) is continuing its efforts against West Nile virus by spraying to kill adult mosquitoes in parts of the West Side on Wednesday, August 27th, 2014. This is the second spraying to occur in the City this season.

Spraying will occur in portions of the Dunning, Montclare, Belmont-Cragin and Austin neighborhoods in the 29th, 30th, 31st, 36th and 37th wards. To download a map of the spray zone, click here.

“When our mosquito traps indicate that the West Nile Virus may threaten human health in a community, we take decisive action,” said CDPH Commissioner Bechara Choucair, M.D. “Even though this summer has been cooler than average, we all must take appropriate precautions.”

Weather permitting, the spraying will begin at dusk on August 27th and will continue through the night until approximately 1:00am, with licensed mosquito abatement technicians in trucks dispensing an ultra-low-volume spray.  

The material being used to control the adult mosquitoes, Zenivex™, will be applied at a rate of 1.5 fluid ounces per acre. It is approved for use by the U.S. Environmental Protection Agency and is used to control mosquitoes in outdoor residential and recreational areas.

Zenivex™ has been used effectively to control disease-carrying mosquitoes and is non-persistent, decomposing rapidly in the environment. The rapid degradation of this product makes it an excellent choice for control of West Nile virus-carrying mosquitoes.  The spray will be applied by licensed mosquito abatement technicians from Vector Disease Control International, a leader in the mosquito control industry. Guiding the crews through the streets will be supervisors from the Chicago Department of Streets and Sanitation.

While the spray is not harmful to people or pets and is routinely sprayed in residential areas across the nation, residents of targeted neighborhoods may choose to stay indoors and close their windows while spraying is underway, as an extra precaution.

“Spraying to kill adult mosquitoes is a sensible and effective component of an integrated pest management program,” added CDPH Environmental Health Medical Director Cort Lohff, M.D. “It is our expectation that this effort will further limit the mosquito population and prevent cases of human illness in Chicago.”

Each year, CDPH conducts a comprehensive West Nile virus surveillance, prevention and control program. In addition to spraying, this includes dropping larvacide in catch basins, which helps limit the number of mosquitoes that can carry the virus, and regularly testing mosquitoes caught in traps throughout the city. By utilizing data the city is able to most efficiently target high-risk areas for the virus.

CDPH reminds residents to take precautions against mosquitoes that may carry the virus, including:

  • Use insect repellent that contains DEET, Picaridin or Oil of Lemon Eucalyptus.
  • Eliminate standing water. This includes emptying water from flowerpots, gutters, pool covers, pet water dishes and birdbaths regularly.
  • Keep grass and weeds short to eliminate hiding places for adult mosquitoes.
  • When outside between dusk and dawn, wear loose-fitting, light colored clothing including long pants, long sleeve shirts, socks and shoes.
  • Check that all screens, windows and doors are tight-fitting and free of holes and tears.
  • Check on neighbors regularly who may need additional assistance, including the elderly.

In 2014, CDPH previously sprayed in the following neighborhoods:

  • Norwood Park (8/20)
  • Portage Park (8/20)
  • Dunning (8/20)

West Nile virus cannot be transmitted from person-to-person. Instead, it is transmitted strictly through mosquitoes. Most mosquitoes do not carry the virus. Additional information on the virus, including symptoms and how to protect against the virus can be found here.

As part of their ongoing response efforts, CDPH will continue to collect mosquitoes from traps located throughout the city and test these mosquitoes for West Nile virus. Using results of these tests, CDPH will determine the appropriate steps to be taken in order to best protect Chicago residents.