These insecticides can also kill bees and other beneficial insects. These products generally require addition precautions, such as, unsprayed buffers around lakes, ponds and streams. Insecticide products containing Bt are toxic only to butterfly and moth caterpillars. It is not toxic to other groups of insects, fish, mammals or humans. In fact, Bt must be taken internally by caterpillars where it causes a natural disease which kills them.
Some people are against any type of insecticide application regardless of the product used.
Bt is toxic to all caterpillars and in some instances killing them would be of concern, especially if any rare moth or butterfly species are involved. If your neighbor objects to spraying, take precautions to avoid the problem and liability of spraying their land by mistake. FTC is a native defoliator of hardwoods trees, especially aspen and basswood. The first recorded outbreak in Minnesota occurred in the late 1870's and there have been five major outbreaks since 1933. Outbreaks usually last three to six years and cause little or no permanent damage to the trees.