Redback spider is now established in Japan: bites can be recognised by a unique sign

Editor—The infamous Australian redback spider (Latrodectus mactans hasselti; fig 1), known for inhabiting the underside of toilet seats and biting bottoms, is now in Japan. More alarming to the Japanese is that these spiders—relations of the black widow—are continuing to breed and spread in the Japanese winter, surviving temperatures as low as 4°C by living near heating systems. The spiders often live near or beneath houses and females will bite defending their nests, which can contain 300 eggs. Japan, like …