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Eight-legged friends or foes?

Lindsey Christianson, Recent M.S. Entomology Graduate

Spiders are common in and around homes this time of year. And while many may be fuzzy, not many people would consider spiders a warm and friendly type of fuzzy. However, in most cases, these creatures fall into the friendly category. Spiders eat insects and other arthropod pests and are considered beneficial. Some spiders inadvertently end up indoors and can be a nuisance by their presence. Two spiders in particular that have been noticeable have been the dark fishing spider and the bold jumper.

The most common species of fishing spider in Minnesota is the dark fishing spider Dolomedes tenebrosus. Fishing spiders are some of Minnesota’s largest and most conspicuous spiders, with bodies that can be up to an inch long. Fishing spiders have two rows of four eyes, and long “sprawling” legs. Dark fishing spiders tend to have brown and black banded legs and chevron markings on the abdomen. They are often found on tree trunks, building walls, fence posts, and near docks. Instead of spinning webs to catch prey, they ambush larger insects that pass by. Fishing spiders are not aggressive towards humans and rarely bite, but they may bite if mishandled or if they feel threatened. The bite is described as feeling similar to a bee sting, but it not harmful. BugGuide has more information and comparison photos for this species.
Dark fishing spider.  Photo: Jeffrey Hahn, UMN Extension
Bold jumpers (Phidippus audax) are often called white-spotted jumping spiders because of the distinct white spot on their abdomen. Bold jumpers are large bodied jumping spiders, ranging from ¼” to ¾” in size. While they are mostly black, they may also be mottled with white on their abdomen and legs.  To identify a bold jumper, look for eight eyes of which two are particularly large.  Bold jumper's chelicerae (fangs) are typically an iridescent green or blue. They are not web-spinners, and hunt small insect prey. Bold jumpers rarely bite but like fishing spiders can if mishandled. Any bites do not produce any lasting effects.
Bold jumper (note the two large eyes facing forward).
Photo: Jeffrey Hahn, UMN Extension

If you occasionally find a spider indoors, regardless of which one you discover, tolerate it as much as possible. If convenient, capture it in a container and release it outdoors. See also the University of Minnesota Extension publication: Common spiders in and around homes.