Hi Roland, BT is short for Bacillus thurigiensis, a bacterium (and it's gene products) that is extensively used in agriculture. In organic gardening you can use a powder of dormant cells like Arnold does and sprinkle/spray on your plants. This bacterium kills insects as it's natural biology. Humans have exploited their ability to do this due to certain set of genes and we have implanted these genes into genetically modified crops to automatically kill the insects without using the bacterium. Nhu, Berkeley, CA -- http://www.flickr.com/photos/xerantheum/ On Sun, Jun 20, 2010 at 2:49 PM, bulborum botanicum <bulborum@gmail.com>wrote: > Hello Arnold > > I am in Europe and maybe a stupid question > what is: > > *I used BT mixed with water and sprayed over the lawn. > > Roland > >