Dolomedes tenebrosus (Dark Fishing Spider)

Summary

The "Dark Fishing Spider," Dolomedes tenebrosus, is frequently mistaken for a wolf spider. These very large, sprawling arachnids are most often found on vertical surfaces: tree trunks, fence posts, bridge pilings, or the exterior walls of buildings, usually at night. There, they wait in ambush for large insects to come within striking distance. They do not spin webs to catch prey, but simply overpower their victims. By day, they hide beneath tree bark, in tree holes, and other sheltered spots. Females spin egg sacs that they carry in their jaws for a time before suspending the sac in a “nursery web” spun among foliage. The female then guards the egg sac, and the spiderlings that emerge from it. After their next molt, the spiderlings disperse and their mother resumes her nomadic lifestyle. This is not an uncommon spider in deciduous forests of the eastern half of the U.S. and adjacent southern Canada.