Theridiidae

Theridiidae, commonly known as comb-footed spiders, is a large and diverse family within the order Araneae. It contains about 2,500 described species in around 100 genera and has a cosmopolitan distribution, occurring in a wide range of habitats from forests and grasslands to human dwellings.

Morphology and web-building: Members typically have a compact body with a rounded abdomen and a relatively small cephalothorax. A hallmark ecological trait is their irregular, three-dimensional cobwebs, often built in sheltered spots such as corners, leaf litter, or buildings. They rely on sticky silk to trap prey and many species use a row of specialized bristles on the hind legs to manipulate silk as they wrap captured prey.

Ecology and behavior: Theridiids are opportunistic predators feeding on insects and other arthropods. Several genera include kleptoparasites that inhabit other spiders’ webs and steal captured prey, notably Argyrodes. The genus Latrodectus includes the notorious widow spiders.

Venom and human interactions: Some Latrodectus species produce medically significant venom; bites can require medical attention. Most Theridiidae, however, are harmless to humans. They contribute to pest control by preying on various insects.

Reproduction and life history: Females lay eggs in silk sacs, which are often guarded or carried until hatching. Development follows standard spider ontogeny with multiple molts, and there is typical sexual dimorphism, with females usually larger than males.

Notable genera: Latrodectus (widow spiders), Steatoda (false widows), Parasteatoda (including Parasteatoda tepidariorum, the common house spider).