Suppression Treatment
The only pesticide used in the Cooperative Suppression Program is Bacillus thuringiensis, most commonly referred to as Bt. There is two reasons for this. First, Bt is short lived when applied to leaf surfaces. Second, Bt will only kill Lepidopteran (moth and butterfly) caterpillars. Bacillus thuringiensis or Bt is a naturally occurring soil bacterium that, when eaten by a moth or butterfly caterpillar causes them to die. Since the gypsy moth butterfly feeds in the canopy of trees, Bt is applied using airplanes or helicopters.
Ultra-violet light breaks down Bt in approximately 7 to 10 days so it is not effective for very long. This fact reduces the risk that a Bt application will effect moth or butterfly larvae that are feeding earlier or later in the season. But it makes application timing important in order to impact the caterpillars when they are most vulnerable.
The application amount is also important. This program tries to minimize the application amount thus reducing cost but also maximizing the application’s effectiveness. A very small amount of the material, 1/3 to ½ a gallon per acre, can be applied in this way and still be very effective. A single application of Bt will kill approximately 80% of the feeding caterpillars. To achieve this, each plane that participates in the Cooperative Suppression Program is calibrated and characterized to assure proper application amount and even distribution of the Bt product. A great deal of care is taken to assure that the Bt application occurs at the right time and at the correct amount.
Threatened & Endangered Species
As stated above, Bt does effect other moths and butterflies that are in the larval stage and feeding on tree foliage that have been treated with Bt. To avoid a problem with threatened and endangered (T&E) species, each proposed treatment block is reviewed by the Michigan Department of Natural Resources, Natural Features Inventory and the U.S. Fish and Wildlife Service for both State and Federal T&E species. This review also looks at the potential impact of low flying planes in areas of T&E species. This information is used to avoid any negative impacts on Michigan’s natural diversity.
Gypsy Moth Management Resources
In addition to using Bt, there are other options available for the management of Gypsy Moth populations. Information pertaining to mechanical control and biological control methods can be found below. Also listed below is a link to pesticide applicator companies licensed to do business in Michigan. These links are provided for information purposes only.
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