The spider family Oecobiidae includes 110 described species (Platnick 2013), including eight that occur in North America north of Mexico. The members of this family have a distinctive appearance and are unlikely to be mistaken for anything else, although they bear a superficial resemblance to Euryopsis (family Theridiidae). Oecobiids have a large anal tubercle that is fringed with long bristles and a subcircular carapace with the eight eyes arranged in a central cluster. (Craig et al. 2005). The bristles spread the capture silk emitted from enlarged posterior spinnerets as the spider wraps its prey (Bradley 2013). Two species (Oecobius cellariorum and Oecobius navus) are widespread in the United States and southeastern Canada—and, in fact, have cosmopolitan distributions (Platnick 2013). In the United States, Oecobius interpellator has been recorded only from Massachusetts and other species of Oecobius are southern. The only other oecobiid genus represented in the United States, Platoecobius, occurs from South Carolina to Florida (P. floridanus), with an apparently undescribed species occurring in southern California. Oecobius are considered to be among the most common human-associated spiders. (Craig et al. 2005)
Oecobius species are found on and under rocks, as well as around human habitation. They typically lie concealed within small sheet webs placed over cavities. The distinctive webs consist of two horizontal sheets. The spider is positioned on the lower sheet and covered by the upper, which has radiating signal lines that give the web a star-shaped appearance. When potential prey touch these lines, the spider emerges and runs rapidly around the prey, periodically changing direction, swathing it in silk. (Craig et al. 2005; Bradley 2013)At least some oecobiids apparently do not construct webs. For example, Platoecobius floridanus, which has been collected under pine scales, is not known to construct a web (Chamberlin and Ivie 1935).
Oecobius are believed to feed heavily on ants, although Liznarova et al. (2013) concluded that the O. navus in their study were simply feeding on locally abundant prey, not necessarily ants; Shear (1970) observed Oecobius in Florida (U.S.A.) feeding on tiny flies. Oecobius spiders often form large aggregations and at least some are reported to be communal. Mating occurs in special webs contructed by the male adjacent to the web of the female. Female egg sacs contain just 3 to 10 eggs, but females provide no maternal care. (Glatz 1967 cited in Shear 1970; Shear 1970)
Craig et al. (2005) note that the recognition by some authors that Oecobiidae includes both cribellate and ecribellate species provided early evidence that the presence of a cribellum was a phylogenetically labile character (its presence apparently being an ancestral trait that has been lost in many lineages) and could not be used to define a monophyletic group (a point later firmly established by Lehtinen 1967).
