Exotic brown widow versus native black widow spiders in urban southern California

The recently introduced brown widow spider Latrodectus geometricus has been successfully spreading throughout southern California urban areas. Various homeowners have reported more frequent sightings of brown widows and less frequent sightings of the native black widow spider Latrodectus hesperus. This raises the question of the possibility of negative interactions between the two species and the current status of each species’ abundance in southern California. This study attempted to explain a relationship between widow spider abundance and environmental factors (temperature, humidity, etc.), and investigated differences in each species’ biology by testing for interspecific competition and possible differences in web area and prey consumption rates.