A spiral of green incense, a faint smoky trail, and that unmistakable summer scent—katori senkō (mosquito coils) are woven into Japan’s warm-season memories. Beyond nostalgia, they’re a clever design born from pyrethrum (chrysanthemum) and refined into a practical tool still used today. What is it exactly, how did it begin, and do people in Japan still rely on it? What Is Katori Senkō? Katori senkō is a mosquito-repelling incense coil. A dried paste—traditionally containing pyrethrum derived from Tanacetum cinerariifolium—is extruded and formed into a spiral. You light the outer tip; it smolders slowly toward the center, releasing a thin, ...
