Investigation continues on new and innovative applications. Chemical control usually implies the use of liquids, gases, powders or granules to control insects. Stomach poisons are used to control chewing insects. Contact poisons are used on both chewing and sucking insects. This method implies contacting the insect directly with the chemical.
Fumigants are actually poison gasses which enter the insects respiratory system.
The nervous system is most affected by these control measures. Have students collect and examine insect damaged plant specimens.