False Widow – Steatoda grossa

Steatoda grossa, commonly known as the cupboard spider, the dark comb-footed spider, the brown house spider (in Australia), or the false black widow (though several other species are known by these names), is a common species of spider in the genus Steatoda.

Common Name: False Widow Spider
Latin Name: Steatoda grossa
Threat Level: Low

It is a cosmopolitan species found in many parts of the world, including North America, Australasia, and Europe. As one of this spider’s common name indicates, the spider superficially resembles, and is frequently confused for, the black widow and other venomous spiders in the genus Latrodectus.

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 markings. Like many spiders, the male is sometimes smaller; But can many times be nearly as long as the females. It measures 4.1-10.0mm 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. Individual S. grossa may shed up to six times (instars) before reaching maturity. They can go several months without feeding, provided they have access to water. A well fed female can lay 3 or more egg sacs each year, in which 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. grossa spiders can live up to six years; the typical lifespan for the male is 1-1.5 years. Males often die shortly after mating.


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