Advance Notice: Briefs

Update: State delays mosquito spraying due to weather

By: - September 27, 2019 3:28 pm

Department of Health and Human Services | Susan J. Demas

Updated, 4:24 a.m. 9/30/19 with the state canceling spraying due to weather.

The Michigan Department of Health and Human Services (DHHS) announced on Sunday that it would delay plans due to inclement weather to conduct aerial spraying in 14 counties across the state because of a mosquito-borne virus. Future plans will be announced Monday.*

The department announced on Friday that it’s seen multiple cases of Eastern Equine Encephalitis (EEE), a dangerous mosquito-borne disease, with a 33% fatality rate for those who contract it from a mosquito bite. As of Friday, nine confirmed cases of EEE in people have been recorded. Three cases resulted in death. In animals 27 cases have been confirmed.

DHHS said that as long as the weather cooperates, aerial pesticide spraying has been scheduled beginning at 8 p.m. Sunday.

Spraying will take place in Allegan, Barry, Berrien, Branch, Calhoun, Cass, Jackson, Kalamazoo, Kent, Lapeer, Montcalm, Newaygo, St. Joseph and Van Buren counties.

Low-flying aircraft will spray starting at 8 p.m. up until 4:30 a.m. the next morning in danger areas, killing adult mosquitoes on contact.

“We are taking this step to help protect the health and safety of Michiganders in areas of the state that are being affected by this dangerous mosquito-borne disease,” Dr. Joneigh Khaldun, the state’s chief medical executive and chief deputy for health, said in a statement. “The continuing number of cases in both people and animals indicate an ongoing risk for EEE exposure. We continue to urge residents to protect themselves against mosquito bites until a hard frost.”

Joneigh Khaldun

The pesticide used is organic, called Merus 3.0. It contains 5% pyrethrin, a chemical found in some chrysanthemum flowers, toxic to insects. Pyrethrins have been legally used in pesticides since the 1950s to manage ants, fleas, moths, flies and other pests.

No health risks are expected during or after spraying, according to DHHS. Those who have sensitivities to pyrethrins are encouraged to reduce exposure by staying indoors during spraying. Surface and drinking water is not expected to be impacted by the spraying.

Because spraying is happening in the nighttime hours, bees are most likely in their hives and fish are not feeding at the surface of the water. It isn’t necessary to bring pets indoors during spraying, but it is recommended to cover small fish ponds.

For more information about the aerial spraying and other health-related information is available in the Frequently Asked Questions document at

DHHS recommends until the winter frost arrives to postpone or reschedule outdoor activities occurring after dusk, when mosquitoes carrying EEE are most active.

Aerial spraying, according to the DHHS has become a necessity to reduce human risk, but it will not eliminate the chances of becoming infected. Residents can protect themselves from the infection by:

  • Avoid being outside from dusk to dawn when infected mosquitoes are most active
  • Applying insect repellents and wearing long-sleeved shirts and long pants while outside when possible
  • Repairing and maintaining screen doors and windows to keep mosquitos away from human contact 
  • Reducing mosquito breeding by destroying breeding sites around the home like buckets with water, old tires, unused kiddie pools or other wet places mosquitoes can lay eggs
  • Protect outdoor eating areas with nets and/or fans

 The DHHS reports that “signs of EEE infection include the sudden onset of fever, chills, body and joint aches which can progress to severe encephalitis, resulting in headache, disorientation, tremors, seizures and paralysis. Anyone who thinks they may be experiencing these symptoms should contact a medical provider. Permanent brain damage, coma and death may also occur in some cases.”

Our stories may be republished online or in print under Creative Commons license CC BY-NC-ND 4.0. We ask that you edit only for style or to shorten, provide proper attribution and link to our web site. Please see our republishing guidelines for use of photos and graphics.

Anna Liz Nichols
Anna Liz Nichols

Anna Liz Nichols is a former Michigan Advance intern. She is a Michigan State University graduate who has reported for several publications, including MLive and Michigan State University’s award-winning student paper, the State News, where she covered the many tendrils of the Larry Nassar sexual abuse scandal.