The deadliest flower in the insect world is a lifeline to farmers—and the planet

National Geographic

The yellow center of the ‘killer chrysanthemum’ contains a natural toxin that is a powerful insecticide.This flower, the pyrethrum plant, contains a potent chemical that is made into an effective, and environmentally friendly, insecticide. PHOTOGRAPHS BY VITO FUSCO BY JACOB KUSHNER PUBLISHED AUGUST 4, 2021• 15 MIN READ

GILGIL, KENYAThe deadliest flower in the insect world is soft to the touch. Each morning in the hills above Kenya’s Great Rift Valley, the white petals of the pyrethrum plant become laden with dew. To the people who pick them, the flower is utterly harmless. But bugs beware: Its yellow center contains a natural toxin that can kill them in seconds.

Discovered in Persia around 400 B.C., the flower produces an active ingredient, pyrethrin, that can be extracted and used to create natural insecticides that farmers spray on crops to protect them from mites, ants, and aphids without harming anyone’s health. Herders rub pyrethrin ointments on their cattle to repel flies and ticks.

In its most common applications, pyrethrin paralyzes pests by attacking their central nervous systems. “If you spray an insect with pyrethrum, for the first 30 seconds it goes mental, incredibly hyperactive, then it falls to the floor,” explains Ian Shaw, managing director of the pyrethrum producer Kapi Limited.

Simply growingChrysanthemum cinerariifolium near your home may be enough to repel parasite-carrying sand flies, whose bite can spread the skin disease leishmaniasis, which affects nearly one million people globally, including many throughout Kenya. The resulting rash can eat away at people’s faces and become fatal if left untreated.

Pyrethrin has also become a powerful tool in the global fight against mosquito-borne diseases like malaria, a parasite that sickens more than a million people and kills more than 400,000 each year, many of them in Kenya. Manufactured in spiral-shaped discs known as mosquito coils, they emit a shroud of smoke like incense that repels mosquitoes but is harmless to humans.

The harvesting of the pyrethrum is done once every two weeks, strictly by hand.