The yellow center of the 'killer chrysanthemum' contains a natural toxin that is a powerful insecticide. 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.