Spider Identification

Asked July 2, 2019, 6:13 PM EDT

I found this spider wedged between two bags of potting soil and wondered if you could help me identify it? We placed a quarter next to it for size reference. Unfortunately I did not see it walk away so I did not see it's size with the legs unfolded. Thank you! Irene Coermann

Wayne County Michigan spider identification

1 Response


That looks like a Dark Fishing Spider, Dolomedes tenebrosus (Araneae: Pisauridae).

Fishing spiders are normally found along the banks of rivers, streams, lakes, wetlands and ponds. They feed primarily on aquatic insects but they will eat tadpoles and small fish if they can catch them. D. tenebrosus is also at home in woodlands and is commonly found in and around structures that are located some distance from water. Fishing spiders are for the most part harmless. They are not known to be aggressive, but any spider will attempt to bite in self-defense if handled roughly. Fishing spiders are usually a shock to people who are unfamiliar with them because of their large size. Some have mistaken them for an escaped pet tarantula or other exotic spiders. Others are concerned that they might be the brown recluse spider, which is very rarely found in Michigan.

Fishing spiders usually enter the structures near ground level and are normally encountered in basements, crawlspaces, and breezeways. These spiders occur in very low numbers, and usually homeowners encounter only one or two of them. Chemical control is not necessary unless large numbers are found.