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