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Property Owner Notification


Dear Property Owner :

The parcel of land described by the code number on this envelope has been included in the 2024 Midland County Spongy Moth Suppression Program. All, or a portion of the property is scheduled to be sprayed with the biological insecticide Bacillus thuringiensis var. kurstaki (B.t.k.) by aircraft in May or early June. Some properties may also be aerially treated with a spongy (gypsy) moth pheromone in mid summer to interrupt the mating process of the spongy (gypsy) moth.

Most of the spraying will be done during the early morning hours when the air is cool and winds are at a minimum. The exact date and time cannot be known in advance as it depends on the insect stage, leaf development, and weather conditions.

Recent advances in aircraft navigation systems have made marker balloons unnecessary. It is much more accurate to use the on board Global Positioning System (GPS) that tracks the aircraft’s position several times a second in relationship to the spray block.
The cockpit computer also checks off each spray block as it is completed. The B.t.k. spray is applied in a very fine mist for maximum coverage of the leaves. It is applied at one quart per acre in droplets only 5/1000 of an inch in diameter. This protects the leaves with about 100 droplets per square inch. Most of the time the spray cannot be seen or felt. Rain has little effect on the spray if it has had time to dry.

B.t.k. is a biological insecticide and is known only to affect the caterpillars of moths and butterflies that are actively feeding at the time of treatment. After ingestion, it destroys the caterpillar’s stomach and the insect slowly dies.  After spray, you may notice a change in the insects after two or three days. They stop feeding, become sluggish and sometimes mass in sheltered areas.        It may take up to a week for those caterpillars that ate the B.t.k. to die.

The pheromone treatment is also accomplished using aircraft spraying of very small bits of porous plastic embedded with the gypsy moth pheromone. With this extra amount of pheromone in the area the male gypsy moths cannot locate the females thus reducing the following year's infestation.

Eradication of the spongy (gypsy) moth is not possible and should not be expected. The intent of the spray program is to give heavily infested home areas some relief from the caterpillar nuisance and to protect other areas from outbreaks when feasible. Homeowners are encouraged to reduce the spongy (gypsy) moth population in their area by ground spraying, collecting and destroying egg masses, and destroying caterpillars; but no single method should be relied on for complete control.

If you do not want your property sprayed in this year’s program, you must contact the Spongy Moth Suppression Program office before April 26, 2024.


There is no additional cost to be included in the spray program. The program is paid for by County funds. If you own more than one parcel of land in the City of Midland or Midland County, please note that only the parcel listed on the envelope is included in the 2024 Program. For a description and location of the parcel number noted on the envelope, contact your Township or City assessor.

Maps showing the areas scheduled for treatment will be available for viewing at the County Community Centers, and on the internet at, under Departments, Spongy (Gypsy) Moth.

Thank you for your cooperation.

Midland County Spongy Moth Suppression Program

County Services Building 220 W. Ellsworth St. Midland, MI 48640-5194, Ph: (989) 689-0223


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