Pyrethrins are a group of insecticidal chemicals derived from chrysanthemums. There is evidence that crushed chrysanthemum seeds were used as an insecticidal agent in China as early as 1000 BC. As one of the oldest and most widely used pesticides in history, it is largely regarded as safe for almost all uses. However, pyrethrins do not persist very long in the environment, and require frequent reapplication for maximum effect.,