Minnesota is home to a diverse population of arachnids, but the vast majority of spiders encountered in the state are harmless to humans. Spiders are not insects but belong to the class Arachnida, distinguished by having two main body segments—the cephalothorax and abdomen—and eight legs. While all spiders possess venom to subdue their prey, only a select few in Minnesota have fangs strong enough and venom potent enough to be considered a medical concern for people. This guide focuses on identifying the most frequently seen species and clarifying the actual threat level posed by the state’s more notorious arachnids.
Minnesota’s Most Frequent Non-Threatening Spiders
Many of the largest and most visible spiders in Minnesota are non-threatening. Wolf spiders (Lycosidae family) are some of the most common, often identified by their dark brown, slightly hairy bodies. They are active hunters that run quickly across the ground instead of building webs to catch prey. These spiders range from one-quarter to one inch in body length, and they may accidentally enter homes during the cooler months.
Another frequent sight, especially near water bodies, is the fishing spider (Dolomedes species), which can be large with a leg span of several inches. They do not spin webs for hunting, instead using their long legs to run across the surface of water to catch insects, small fish, or tadpoles. Their venom is not considered medically significant to humans.
Orb weavers (Araneidae family), such as the bright yellow and black garden spider (Argiope aurantia), build the large, circular webs seen in gardens and fields. These spiders have large, swollen-looking abdomens and construct their silk traps outdoors. Despite their striking colors and size, they are not aggressive and rarely bite unless they are severely provoked or trapped.
Cellar spiders (Pholcidae family), often called “daddy long-legs,” are commonly found indoors in cool, damp, and dark areas like basements and garages. They have very small bodies and extremely long, delicate legs, spinning irregular webs in corners. Their fangs are too small to penetrate human skin effectively, and they are beneficial for preying on other indoor insects and spiders.
The Question of Medically Significant Venomous Species
The most significant concern regarding spiders in Minnesota centers on the Northern Black Widow (Latrodectus variolus), which is the only species in the state whose venom is considered medically significant. The female Northern Black Widow is glossy black and possesses a characteristic red marking on the underside of its abdomen. Unlike the Southern Black Widow, this marking is often broken into two separate triangles rather than a complete hourglass shape. This species is rare, typically being found only in the warmer, southeastern counties. Black Widows prefer to build their webs in dark, undisturbed areas, such as woodpiles, under rocks, in sheds, or in crawl spaces. Bites from this spider are uncommon, as they are not aggressive and will only bite when trapped or accidentally disturbed.
The Brown Recluse spider (Loxosceles reclusa) is generally not established in Minnesota. The state falls far outside the Brown Recluse’s native range, which is primarily concentrated in the south-central United States. Reported sightings in Minnesota are nearly always misidentifications, usually of common non-threatening spiders like the Hobo spider or various Sac spiders. The cold climate of the region limits the ability of the Brown Recluse to establish a sustainable outdoor population.
Bite Management and Safety Precautions
Since most spider bites are from non-venomous species, they typically result in only minor symptoms, such as localized redness, slight swelling, and mild pain. The initial first aid for any spider bite involves cleaning the wound thoroughly with mild soap and water to prevent secondary infection. Applying a cool, damp cloth or ice pack to the affected area for 15 minutes each hour can help reduce both pain and swelling. An over-the-counter pain reliever can be taken for discomfort, and an antihistamine may help if the area becomes itchy.
To minimize the risk of being bitten, shake out clothing, shoes, and towels before use, especially if they have been left in a garage or basement. Wearing gloves when working near woodpiles or in areas that have been long undisturbed is also a good precaution.
You should seek professional medical attention immediately if you suspect a bite from a Black Widow or if you develop severe, systemic symptoms. These symptoms include intense pain, severe muscle cramping, abdominal rigidity, nausea, or vomiting. Medical consultation is also necessary if the bite site shows signs of a spreading infection, such as increasing redness, warmth, or streaks moving away from the wound.