Thiamethoxam is a group 4A, a neonicotinoid insecticide. It works by use of the insects' acetylcholine receptors, making is selectively toxic to insects but not mammals. As a broad-spectrum systemic insecticide in weed control, it is absorbed rapidly by plants and transported to all of its parts, the insects feed on the weed, and it enters the insect's system, and paralyzes it. As an insect bait, with Thiamethoxam, it is ingested, with death following.