If you were designing a new insecticide absorbed via the respiratory system in arthropods, the killing chemical would enter the invertebrate through the Tracheae.
The tracheae, which extend inward from the spiracles and typically divide into smaller branches with a diameter of 2 microns or less, are the tracheal system's largest tubes. Since tracheae are made of ectodermal tissue, they contain a cuticular lining that is shed with each moult.
The respiratory system of insects is distinct from the circulatory system, and gas exchange occurs through a network of internal tubes called tracheae.
Every cell in the body receives oxygen-containing air thanks to a sophisticated network of tubes. Through holes that resemble valves in the exoskeleton, air enters the insect's body.
