1.   Synthesized by British scientists who were searching for new insecticides after World War II, VX can contaminate an area for days.

2.   The Bartlett company has pioneered the application of the new Merit insecticide in the soil around the base of the hemlock tree.

3.   The new insecticides have been used successfully on cotton farms in Israel for more than five years.

4.   Over time, some insecticides become less effective at killing insects, and new insecticides must be developed.