Invasive insects, like the gypsy moth, pose a serious threat to the economy and environment of Minnesota. Without treatment, a population can get out of control and defoliate large sections of forest.

Based on careful review, the MDA uses the bacterium Btk, formulated in the product Foray 48B, for gypsy moth control.

Will the product harm humans, other mammals, fish, birds or honeybees?

No, Btk is not toxic to humans, mammals, fish, birds, or honeybees. Btk only works under the alkaline conditions present in the stomach of insects in the caterpillar stage of development. This alkaline condition is not present in the stomachs of humans, mammals, fish, birds, or honeybees, which is why the Btk does not affect them.

What about other moths and butterflies?

To have any effects, caterpillars must be actively feeding within approximately two weeks after treatment, they must eat the Foray, and they must be susceptible to the bacteria. The MDA works with the Minnesota Department of Natural Resources and the U.S. Fish and Wildlife Service to identify and evaluate impacts to any threatened or endangered species, and ensure that no sites of sensitive, threatened, or endangered species of moths and butterflies overlap with this year’s proposed Foray treatments.

Without treatment, gypsy moth caterpillars can quickly ravage the vegetation that these native moths and butterflies depend on.

Will more treatments be necessary?

Minnesota first used Btk for gypsy moth in 1984. Since then, approximately 50 sites in the state have been treated for the insect. Only one area has needed to be retreated. Why was a retreatment needed? It is likely the original treatment area was too small to eradicate all the gypsy moths. The MDA strives to find the right balance when drawing treatment areas.

We do our very best to design our management blocks as small as possible yet large enough to avoid missing the gypsy moth population and having to conduct a second year of application. In addition, we want to treat the population as quickly as possible to avoid the population from expanding and thus resulting a much larger treatment area in following years.

Will the product harm my vehicle, home, and other items outside?

The spray residue is not harmful to humans, animals or outdoor structures. The spray can be easily washed off. It will show more readily on dark colored vehicles and it can be washed off. If left in the sun for a few days without washing, the spray deposit on vehicles may have to be rehydrated in order to remove it. Take an old bath towel and soak it in sudsy water and drape it over the vehicle for a few minutes. This will help soften the spray deposit and it can be removed. More ‘elbow grease’ may be required if the spray deposit is left on the vehicle for several days.