False Widow

Steatoda grossa, the cupboard or false widow spider, is a theridiid closely related to true widows. Females are 6–10 mm with a shiny, bulbous purplish-brown to near-black abdomen marked with faint cream crescents or chevrons and no hourglass — the key separation from Latrodectus. Males are smaller and more slender with longer legs. Females live two to six years, an unusually long span, and produce several off-white spherical egg sacs of 40–100 eggs; development to adult takes several months and is slowed markedly below 18°C.

False widows build tough, irregular cobwebs with sticky gum-footed lines in the same voids widows favour, and they routinely prey on other spiders — including juvenile black widows — as well as woodlice, ants and beetles. They are sedentary and nocturnal, and bites are rare and typically no worse than a bee sting, causing local pain without systemic latrodectism. Because they are so often mistaken for widows, they are the most common cause of misidentified 'widow' calls, and confirming the absence of an hourglass prevents unnecessary alarm and over-treatment.