Parasteatoda tepidariorum is a cob-web weaving spider abundant in both urban and rural areas across the temperate regions of the globe. They are typically found in sheltered areas such as garages, porches, caves, and between stones where they are able to construct a three-dimensional web structure. Because these organisms function as both predator and prey, proper habitat selection is vital for the survival of the individual. Individuals of this species must find locations that are conducive to high levels of prey availability but also sheltered to avoid undue predator exposure. In their natural habitats, these locations tend to be shaded. Because these spiders do not readily move locations once their webs are built, proper habitat choice is important. With this information in mind, these apparent preferences in habitat may infer specific inclinations towards light exposure. These interactions, however, have not been thoroughly investigated. Because of the natural variation of light levels in these habitats, we hypothesize that these spiders may be utilizing light levels in habitat choice. In this study, we aimed to detect any indications of preferences using adult female P. tepidariorum. Spiders were captured in Sullivan and Washington counties in Tennessee and were returned to the lab where they were maintained under standard conditions prior to being placed into the experimental chamber. This experimental chamber consisted of two concentric circles that created a consistent tunnel structure for web-building throughout. A light gradient was constructed so that one side of the circular tunnel had the maximum light exposure of 410 lux and the other side faded to 0 lux. The chamber was placed in a controlled environment with a 12 h light:12 h dark cycle at ~24° C. One spider was placed into the choice chamber at a time and allowed three full days to explore and choose an environment in which to build a web. After three days, the location of the spider was recorded, and the spider was removed. The chamber was cleaned with ethanol and allowed to dry before another spider was placed into the chamber. Each spider was repeated at least twice. All individuals built webs in the dark half of the arena, and there was a significant preference for very low light (but not complete darkness). These results indicate that P. tepidariorum may select habitats based on light exposures. By investigating these preferences, we are able to get a better understanding of how P. tepidariorum interpret their environment to choose proper web locations.

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