Mosquito Control

Rebecca Brandt, Manager

810 Livingston Avenue
Bay City, Michigan 48708-6380
Voice: (989) 894-4555
Fax: (989) 894-0526

Treatment Schedule

Adulticiding treatment for September 20th will occur in the following townships: 

Portsmouth, Bangor, Monitor, Kawkawlin, Williams, and Fraser




 **Residents who prefer to opt out of mosquito control may submit an application for "no-spray status", found at the bottom of this page**

Bay County Mosquito Control manages mosquitoes using an Integrated Mosquito Management (IMM) approach, which means using a combination of techniques to control mosquitoes such as education, source reduction, larviciding (the control of mosquitoes in the larval stage), and adulticiding (the control of mosquitoes in the adult stage).  Although efforts are geared toward limiting habitat available to mosquitoes through education and source reduction (dumping water from containers or covering them), it is sometimes necessary to manage mosquitoes in other ways.


Larviciding is the term used to describe controlling mosquitoes in standing water while in the larval or pupal stage of development, before they emerge as adults.  Virtually any natural or man-made collection of standing water can breed mosquitoes including ponds, flooded woodlots, flooded fields, drains, ditches, catch basins, containers, neglected swimming pools, etc.  Nearly 70% of Bay County Mosquito Control's operations are spent larviciding, with over 15,000 breeding sites inspected annually.  Approximately 10-15% of these sites require treatment with a control material.  Larviciding activities vary depending on the time of year.

   SPRING AERIAL LARVICIDING - Aerial larviciding of seasonally flooded woodlots signals the beginning of the mosquito control season and nearly 50,000 acres are treated throughout Bay County in April.  Only flooded woodlots are treated at this time since that is the only habitat that breeds the spring species of mosquitoes.  The aerial operation targets larvae before they reach the adult, biting stage using a bacterial product known as Bti.  The aerial program has been in place for over three decades in Bay County and remains the best way to dramatically decrease numbers of spring mosquitoes.  Woodlots not part of the aerial program are treated by foot crews.

   SUMMER LARVICIDING - Technicians conduct daily mosquito surveillance in a variety of aquatic habitats.  These sites include backyard inspections of pools, containers, and ponds and other more permanent habitats like ditches, flooded fields, woodlots, and marshes.  Other summer larviciding operations include treatment of catch basins throughout Bay County, imperative in reducing the risk of Culex mosquitoes, a known disease vector.  Catch basins can be found along streets, in parking lots, and in backyards.  In 2017, a total of 30,382 individual catch basins were treated with naturally-occurring products.  After major rainfall events, priority is given to treatment of roadside ditches throughout the County, a major habitat of floodwater mosquitoes.  In 2017, 3,297 miles of roadside ditches were treated using truck-mounted units.


Adulticiding, also known as fogging, is an aerosol application of insecticide designed to control adult mosquitoes in flight.  Materials are applied in very small amounts (about 1-2 ounces of active ingredient per acre) using Ultra Low Volume (ULV) equipment.  Control materials used do not persist in the environment and are quickly broken down in sunlight.  Fogging is performed by technicians certified by the State of Michigan and insecticides are applied in strict conformance with label requirements.  Applications are conducted at night when mosquitoes are most active, beginning after sunset and ending around 1 a.m.  Treatment areas vary each night as multiple factors such as trap counts, disease activity, rainfall data, and citizen requests assist in determining fogging routes.  Typically, it takes three or four evenings to complete the treatment of an individual township as townships are made up of several spray routes that allow for efficient treatment application.Treatment is weather-dependent as wind, cool temperatures, and rain can postpone nighttime operations.  The schedule, therefore, may be altered due to weather delays or technical difficulties, at the discretion of Bay County Mosquito Control.  Product labels and Safety Data Sheets (SDSs) can be found on the "Product Labels" link on the Mosquito Control home page.


Residents who prefer to opt-out of treatment by MosquitoControl may request “no-Spray” status by returning the form below and placingyellow, reflective signs at both ends of their property. These signs indicate to our drivers not to treatthis property. It is the property owner’s responsibility to place the signs atproperty boundaries so they are visible to our drivers. Bay County Mosquito Controlhonors all no-spray requests, no matter the reason.

No-spray status must be renewed annually to ensure accuracy. Mosquito Control will send a renewal lettereach spring which must be completed and returned to the office prior to thestart of the treatment season. The initialrequest for no-spray status can be made at any time.

Return the no-spray form below for inclusion on the no-spraylist.  Once received, Mosquito Control will make arrangements for you to receive yellow, reflective signs.

Mosquito Control No Spray Form.pdf