Pyrethrins is a mixture of pyrethrins, which are insecticidal compounds derived from the Chrysanthemum flower. Pyrethrins induce mortality of C. fatigans mosquitoes when used at a concentration of 200 mg/ft alone or in combination with the synergist piperonyl butoxide on glass, wood, or mud panels, with the effect persisting for 3-4 weeks. Pyrethrins are toxic to rats via oral administration (LCs = 700 and 1,030 mg/kg for female and male rats) and inhalation (LD = 3.4 mg/L), as well as to rainbow trout (LC = 52.2 µg/L). Formulations containing pyrethrins have been used in the control of insects in agriculture and horticulture.