Tennessee’s diverse landscape, from the Appalachian Mountains to the Mississippi River, supports a wide variety of spider species. While many of these residents are harmless, their presence often causes public concern. This guide focuses on the most commonly encountered spiders in the state, detailing how to identify them and offering practical advice on safety around the few medically significant species. Understanding their habits and appearance helps separate unwarranted fear from genuine caution.
Medically Significant Species
The brown recluse and the black widow are the two spiders in Tennessee whose venom is considered a health concern for humans.
Brown Recluse (Loxosceles reclusa)
The brown recluse is a small spider, typically measuring a quarter to three-quarters of an inch in length, with a light to medium brown color. It is best identified by a dark, violin-shaped marking on its cephalothorax, with the neck of the violin pointing toward the abdomen. This spider has a unique eye arrangement, possessing six eyes organized in three pairs, rather than the eight eyes common to most spiders. Recluses prefer secluded, dark, and dry areas like closets, attics, basements, and woodpiles. They spin irregular, messy webs that serve as a retreat and bite only when trapped.
Black Widow (Latrodectus species)
The female black widow is easily recognized by her glossy black body and a distinctive, bright red or orange hourglass mark on the underside of her rounded abdomen. Females can measure up to an inch and a half across with their legs extended, and their venom contains a neurotoxin. Black widows construct irregular, messy webs in undisturbed areas, often low to the ground in places like crawl spaces, sheds, garages, and under patio furniture. A bite from either species requires immediate medical attention, especially for children, the elderly, or those with compromised immune systems.
The Most Frequently Encountered Spiders
Many spiders encountered indoors or in yards are harmless, despite their size or appearance.
Wolf Spiders (Lycosidae)
Wolf spiders are large, robust, and hairy, ranging from a half-inch to two inches in size, with coloration typically a blend of brown, gray, and black for camouflage. These spiders are active hunters that patrol the ground for prey and do not build webs to capture food; instead, they rely on their excellent eyesight and speed. Female wolf spiders are often seen carrying their egg sac attached to their spinnerets, a distinctive trait that is non-threatening.
Orb Weavers (Araneidae)
Orb weavers are common outdoor spiders, known for constructing the classic, large, wheel-shaped webs often seen in gardens and between shrubs. These spiders vary widely in appearance, with some species displaying bright yellow and black patterns, like the yellow garden spider. Orb weavers are non-aggressive and their venom is not medically significant to humans, making them beneficial predators of garden pests.
Cellar Spiders (Pholcidae)
Cellar spiders, sometimes called “daddy longlegs,” are often found in basements, crawl spaces, and garages, building loose, messy webs in ceiling corners. These spiders are characterized by their small, pale-yellowish to gray bodies and extremely long, thin legs, which can be many times longer than their body length.
Distinguishing Features and Typical Habitats
Differentiating between medically significant and harmless spiders relies on contrasting a few specific attributes. The brown recluse is small and delicate with no hairiness, whereas wolf spiders are significantly larger, much hairier, and have a more robust build. While both are brown, only the recluse possesses the distinct violin-shaped marking on its back; wolf spiders have a generalized striped or mottled pattern.
Web structure also provides a clue: the black widow and brown recluse build irregular, messy silk retreats close to the ground or in secluded clutter. This contrasts sharply with the large, symmetrical, and organized orb webs of garden spiders. Recluses and widows prefer dark, undisturbed indoor storage areas. In contrast, orb weavers are typically found outside in open areas, constructing their elaborate webs to catch flying insects. Wolf spiders are ground hunters, and cellar spiders are easily distinguishable by their disproportionately long, thin legs and habit of hanging upside-down in damp, quiet spaces.
Bite Prevention and Safety Measures
Minimizing encounters with spiders, particularly the two medically significant species, relies on reducing clutter and sealing entry points around the home. Spiders are attracted to undisturbed, dark environments, so reducing piles of wood, debris, and boxes both inside and outside the house eliminates many potential hiding spots. Sealing cracks and crevices in the foundation, around utility pipes, and ensuring window screens are intact prevents spiders from entering the structure. Since recluses often hide in stationary items, shake out clothing, towels, and shoes before use, especially those stored in a closet or on the floor.
If a bite is suspected, wash the area thoroughly with soap and water to prevent secondary infection. Applying a cool compress or ice pack can help reduce localized swelling and pain. While most spider bites are harmless and managed with basic first aid, seek medical attention promptly if the spider is identified as a black widow or brown recluse. Also seek attention if severe symptoms develop, such as intense muscle cramping, a spreading blister, or systemic reactions like fever. If possible, safely collect the spider for professional identification, as this information is invaluable to medical providers.