False Black Widow

Like black widows, the female S. grossa is 6-10.5 mm in length and dark colored with a round, bulbous abdomen. Typical coloration ranges from purplish brown to black, with light-colored markings. Unlike black widows, redbacks, and other Latrodectus species, S. grossa does not have a bright red hourglass pattern or any other bright, distinctive markings. Like many spiders, the male is sometimes smaller but can many times be nearly as long as the females. It measures 4.1-10.0 mm in length and is thinner than the female. The two sexes are colored similarly; however, the sexually mature male almost always has lighter, more reddish-coloured legs than the female. S. grossa spiders may shed up to six times (instars) before reaching maturity. According to Charles Hogue (Insects of the Los Angeles Basin, 1993), it reportedly preys on black widows. They can go several months without feeding, provided they have access to water. A well-fed female can lay three or more egg sacs each year. Each egg sac typically contains between 40-100 eggs. The mother can often be observed watching her eggs for hours, even days, at a time once the eggs start changing color and grow close to hatching. At normal household temp/humidity, an egg will usually hatch within a month of being laid. The spiderlings are independent from time of hatch. Female S. …

S. grossa is a cosmopolitan species. It is native to Europe and much of temperate Asia. It has been introduced to North and South America, Macaronesia, Africa, New Zealand and Hawaii. In South Africa, the species has been sampled from the Grassland, Fynbos, Nama Karoo, and Savanna biomes.

Steatoda grossa was selected by director Sam Raimi to represent the radioactive spider whose bite transforms Peter Parker in the 2002 movie Spider-Man. The spider used for filming was painted with red and blue makeup.