People and insects have more in common than you might think. Insects need to breath oxygen, convert food to energy and regulate their movement and body functions with a nervous system that is very similar to ours. It should come as no surprise the chemicals that kill insects by asphyxiation, stopping energy production or affecting nerves can be toxic to humans. Insecticides can function as stomach poisons, contact and residual contact poisons, and as gasses that are taking in during respiration (fumigants). For contact insecticides it helps to be lipo-philic (fat loving).Insects adsorb these liphilic compounds through their skin. Understanding how insecticides work is important to help select products that are less toxic and also prevent or slow down the development of insecticide resistance in insect populations.