Updated 10/08/09

Btk Facts

For more information, e-mail us or call (800) 443-6684.

To view PDF files, download Acrobat Reader.

What is Btk?

Btk (Bacillus thuringiensis kurstatki) is a naturally occurring bacterial pathogen of the gypsy moth. It commonly occurs in soils and on plants throughout the world. It is employed in a biological insecticide used to eradicate the gypsy moth and many other insect pests. Widespread use of Btk to control the gypsy moth began in the 1970’s and has been applied to millions of acres of forest in the east and mid-west since. Over 500,000 acres were treated in the eastern U.S. in 2008 - more than twice the area of Mount Rainier National Park.

Why Choose Btk?

Btk is the most effective biological treatment for eradication of the gypsy moth. First used in Europe in 1938, Btk is used worldwide in both forestry and agricultural applications. Numerous studies have shown Btk to be very low risk to human health. Btk will not harm beneficial insects such as bees, lady beetles, ants or parasitic wasps. It is also not harmful to animals, birds or fish.

Is Btk organic?

Yes, the Organic Materials Review Institute (OMRI) has determined that the formulation of Btk “Foray48B®” is organic. OMRI is a national nonprofit organization that approves products that are used on operations that are certified organic under the USDA National Organic Program.

How does Btk work?

1. Caterpillar consumes foliage treated with Bt (spores and crystalline toxin).
2. Within minutes, the toxin binds to specific receptors in the gut wall, and the caterpillar stops
   feeding.
3. Within hours, the gut wall breaks down, allowing spores and normal gut bacteria to enter the
   body cavity: the toxin dissolves.
4. In 1-2 days, the caterpillar dies as spores and gut bacteria proliferate in its blood.