The spider family of Theridiidae has a world-wide distribution and contains more than 2000 species. They construct irregular webs for catching other arthropods, using a comb-like structure on the last pair of legs. Any prey caught in the web is first secured with sticky silk and then injected with a toxin.
Some species from the genus Latrodectus ("widow" spiders) may be found in houses. They can bite humans when they feel threatened and are accidentally touched. The injected poison causes severe pain and is on rare occasions deadly.
This page only deals with medically important spiders. For species of Theridiidae which are considered useful predators of insect pests see the page Theridiidae (predators).
The following genera are currently entered under Theridiidae (veterinary/medical):