Most pesticides contain some form of chemical or organic compound in them that is toxic or detrimental to insects; sometimes there are a combination of compounds. This is referred to as the "active ingredient" of the pesticide.
They are able to kill insects in a number of ways depending on the insect and the formulation.
Some ways that pesticides work inlcude:
- Stomach poison (via ingestion)
- Fumigants (via inhalation)
- Neuro-toxins (via ingestion or inhalation)
- Metabolic disruption (via ingestion or inhalation) - here the product works by preventing some part of the natural life-cycle of the insect - e.g. preventing it from pupating, this is a slower action than other pesticides.