Tennessee is home to a rich diversity of spider species. While hundreds of species exist across the state, only a small fraction poses any risk to human health. The vast majority are harmless and play a beneficial ecological role by controlling insect populations. Understanding the characteristics of the most common species helps residents coexist peacefully with these arachnids.
The Medically Significant Species
Only two spider species in Tennessee are considered medically significant due to their venom: the Brown Recluse and the Black Widow.
The Brown Recluse (Loxosceles reclusa) is light to medium brown, measuring between a quarter and three-quarters of an inch long. It is identified by a dark, violin-shaped marking located on its cephalothorax. This spider is not aggressive and usually only bites when accidentally trapped against the skin, often while handling stored items. The bite may go unnoticed at first, with symptoms developing over two to eight hours, presenting as redness, pain, and blistering. In approximately 10% of cases, the bite can lead to a necrotic lesion where the tissue dies, which may take months to heal. Brown Recluses prefer dark, undisturbed locations like closets, attics, basements, and inside stored boxes or woodpiles.
Black Widow spiders in Tennessee are typically the Southern Black Widow (Latrodectus mactans) or the Northern Black Widow (Latrodectus variolus). The female Black Widow is glossy black with a distinct red hourglass marking on the underside of her spherical abdomen. The female’s venom affects the nervous system, causing symptoms like severe muscle cramping, abdominal pain, tremors, and sweating. Fatalities are extremely uncommon because the amount of venom injected is small. Like the Brown Recluse, Black Widows are reclusive, building irregular, tangled webs in secluded, sheltered areas such as sheds, crawl spaces, and under outdoor furniture.
Common Non-Threatening Spiders
Many frequently encountered spiders in Tennessee are harmless. Wolf Spiders (Lycosidae) are large, robust hunters often mistaken for dangerous species due to their hairy appearance and size, sometimes reaching two inches across including their legs. They are agile ground-dwellers that chase down insects rather than building webs to catch prey. While they may deliver a painful bite if provoked, their venom is not considered medically significant to humans.
Orb Weavers (Araneidae) are common in gardens and fields, recognized by the large, intricate, wheel-shaped webs they construct. Species like the Black and Yellow Garden Spider are particularly striking with their bold coloration and can make webs several feet in diameter. Despite their intimidating size and visible webs, Orb Weavers are docile and pose no threat to people.
Jumping Spiders (Salticidae) are small, compact arachnids with excellent vision, known for their ability to leap many times their body length to pounce on prey. They are often seen basking on sunlit surfaces. Cellar Spiders (Pholcidae), commonly called “daddy longlegs,” have extremely long, thin legs. They build messy, tangled webs, usually in dark, damp areas like basements and crawl spaces. They are not dangerous and are beneficial, sometimes preying on other spiders.
Habitat and Seasonal Activity
Spider activity in Tennessee is influenced by temperature and insect prey availability, causing seasonal fluctuations in visibility. While spiders are present year-round, their numbers are most apparent from late summer through early fall. This peak occurs because warmer weather boosts insect populations, and male spiders mature and wander in search of mates, increasing the chance of human encounters.
Many species naturally inhabit wooded areas, gardens, and water sources. When outdoor conditions become less favorable, especially as temperatures drop in the fall, spiders seek more stable environments. They often move into homes looking for shelter or moisture. Indoor habitats are typically dark, undisturbed areas with minimal foot traffic, such as cluttered closets, storage rooms, attics, and crawl spaces.
Prevention and Safety Measures
Minimizing the presence of spiders involves reducing access points and eliminating their food sources and shelter. A primary preventive step is sealing small cracks, gaps, and entry points around windows, doors, and the foundation using caulk or weather stripping. Repairing torn window and door screens also prevents easy access.
Reducing clutter in areas like basements, garages, and attics removes the dark, undisturbed hiding spots that spiders favor. Outside, trim back vegetation so shrubs and tree branches do not touch exterior walls, which spiders use as bridges. Switching exterior lights to yellow or sodium vapor bulbs helps reduce the spider’s outdoor food source by attracting fewer flying insects.
If a bite from a medically significant species is suspected, clean the area gently with soap and water and apply a cold compress to reduce swelling and pain. Seek professional medical attention immediately if the victim is a young child, elderly, immunocompromised, or if severe symptoms like muscle cramping or systemic illness develop. Capturing the spider for identification, if safe, can assist medical personnel.