A survey was done of the environments and substrata occupied by Loxosceles intermedia Mello-Leitão, 1934 and Loxosceles laeta (Nicolet, 1849) (Araneae: Sicariidae) in urban woods and anthropic constructions in Curitiba. In total, 2,099 trees, 364 decaying logs as well as stones and roots, built-up areas, and wasteland in six urban parks and 60 residences were inspected. In total, 1,775 m² of vegetation was inspected, but spiders and their vestiges were collected only in and around buildings in urban parks and residences. L. intermedia was more common than L. laeta and occurred both indoors and outdoors, whereas L. laeta was more common indoors in wooden houses. The two species did not occur in the same microhabitats, although both preferred paper, wood, and construction materials. Spiders collected in urban parks were heavier than those collected in residences, although only males collected in urban parks were larger than those from residences. The lack of vestiges indicative of a previous occupation in the urban parks suggested that both species occupied primarily the anthropic environment where they found numerous substrata that offered thermal isolation and suitable conditions for web fixation, ecdysis, and reproduction.