History

• Pyrethrum has been in use as an insecticide for over 200 years, according to Jack DeAngelis, PhD, retired Oregon State University Extension Entomologist. It was first used in central Asia. During the Napoleonic Wars it was used by French soldiers to prevent and control infestations of lice and fleas.
  
  

Use

• Pyrethrum is toxic to most insects, and is commonly used to kill or repel ticks, flies, mosquitoes and bees. Its effectiveness is limited, however, by its instability. Pyrethrum lasts only hours in sunlight. DeAngelis says this limits its use in agriculture, but it remains a viable option for indoor plants or when used at night.
  
  

Warning

• According to the New York State Agricultural Experiment Station at Cornell University, pyrethum is one of the less toxic insecticides. However, they still advise care when handling it. While it is not harmful if exposed to the skin, it can be dangerous if inhaled. Symptoms of excessive pyrethum exposure can include tremors, convulsions, trouble breathing and a headache.