# Dark fishing spider (Dolomedes tenebrosus) > A large, nocturnal nursery-web/fishing spider common around buildings and woodland edges in eastern North America; not aggressive to people. Source: https://insectscanner.com/species/dark-fishing-spider/ (updated 2026-10-10) ## Is it dangerous? **Mild bite.** Bites are uncommon. If bitten, symptoms are usually local pain, redness and swelling similar to a bee sting. Severe allergic reactions are possible but rare; seek medical care for progressive swelling, intense pain, numbness, or signs of allergy. Clean the wound, apply ice to reduce swelling, and seek medical advice if needed. **Pets:** Generally not dangerous to cats or dogs. A bite could cause localized pain and swelling; monitor pets and consult a veterinarian if the pet shows unusual behavior, persistent pain or swelling. ## Quick facts - Scientific name: Dolomedes tenebrosus - Order: Araneae (Spiders) - Family: Pisauridae (Fishing and nursery-web spiders) - Size: Body length: females about 15-26 mm, males 7-13 mm; legspan up to about 90 mm - Colours: Dark brown, Medium brown, Tan, Cream - Habitat: Woodland edges, stone walls, rock piles, stream margins, and human structures such as basements, garages and porches. - Range: Eastern and central North America (United States and southern/central Canada). - Active: Late spring through autumn; mainly nocturnal. - Lifespan: About 1-2 years in the wild (one season to overwintering adults depending on sex and local climate). - Effect on plants: Harmless - Pest: no ## Overview Dolomedes tenebrosus is a large, long-legged spider in the family Pisauridae. It commonly lives at the edge of wooded areas, stone walls, and around houses; it hunts by waiting on vegetation or structures and grabbing insects and other small prey. Although called a "fishing" spider, it is more often found on land than on water, unlike some related Dolomedes that routinely run on water. It is mostly active at night and often hides in crevices or inside buildings during the day. This species can appear near human homes because it finds shelter in basements, garages, sheds and porch eaves and because artificial lights attract the insects it feeds on. Bites are uncommon and the species is not considered dangerous to people; documented bites produce localized pain and swelling similar to a bee sting in most cases. Natural predators include birds, small mammals, larger spiders and parasitic wasps. ## How to identify it Adults are robust with long legs and a flattened body. Ground colour ranges from medium brown to dark brown with a paler dorsal pattern: a pale central band or chevrons on the abdomen and lighter markings on the carapace. Legs are banded or uniformly brown and covered with fine hairs. Females are larger and bulkier than males. Eye arrangement typical of Pisauridae (two rows). Females carry the large round egg sac in their jaws (chelicerae) and later hang it in a silk nursery web, which they guard until the spiderlings disperse. - Large, long-legged spider with a flattened body and legspan up to about 90 mm. - Distinct pale dorsal banding or chevrons on a dark brown abdomen and lighter markings on the carapace. - Habitat at woodland edges, rock walls, or near human structures; often found hiding in cracks during the day. - Eye pattern and hunting posture typical of Pisauridae: legs extended forward and sideways when at rest. ## Lookalikes - **Six-spotted fishing spider** (Dolomedes triton): D. triton lives on the water surface of ponds and has a pale stripe along each side of the body and rows of white spots on the abdomen; D. tenebrosus is darker, more mottled and often found away from water. - **Striped fishing spider** (Dolomedes scriptus): D. scriptus has distinct pale W-shaped marks across the abdomen and is usually found along streams; D. tenebrosus has darker, less crisp chevrons and is common on trees and buildings. - **Wolf spiders (large Pardosa or Trochosa species)** (Various Lycosidae): Wolf spiders have sturdier bodies and carry their egg sac attached to the spinnerets (rear), while D. tenebrosus carries its egg sac in its jaws and has longer legs and a flatter resting posture. ## Life cycle - **Egg sac:** Female produces a large round silk egg sac and carries it in her jaws (chelicerae) until the eggs are close to hatching, then hangs it in a nursery web and guards it. - **Spiderling and adult:** Spiderlings hatch and disperse from the nursery web; juveniles moult several times to reach adulthood. Adults mate in late summer and autumn; females may survive to the following spring in some climates. ## Diet and predators - Young eat: Small insects and other tiny arthropods - Adults eat: A variety of insects and other arthropods; occasionally small frogs or tadpoles are taken by larger individuals - Predators of the young: Parasitic wasps, ants, ground beetles, and birds - Predators of adults: Birds, larger spiders, shrews and other small predators ## Effect on plants and gardens Feeds on insects and other arthropods; not a herbivore and does not damage plants. Helps control pest insects. ## Where and when to find it Look under porch eaves, in basements, garages, rock walls, leaf litter and along stream margins. Egg-carrying females hide in crevices and under boards. - Best time: Late spring through autumn, especially at night when they hunt. - Tips: Use a flashlight at night to spot active individuals. Photograph them from above or the side to capture body pattern and leg span; avoid handling—use a jar and a piece of cardboard to relocate if needed. ## Fun facts - Although called a fishing spider, Dolomedes tenebrosus is more often found on land and around buildings than actually on water. - Females carry their egg sac in their jaws and then build a silk nursery for the young, a behavior that gave their family the name 'nursery-web spiders'. - They are excellent ambush hunters and can catch surprisingly large prey relative to their body size. ## Frequently asked questions ### Are dark fishing spiders dangerous? Only mildly. They are not considered dangerous to humans; bites are rare and usually cause only mild, temporary pain and swelling. ### Do dark fishing spiders bite? They can bite if provoked or handled roughly, but bites are uncommon. Most bites cause localized pain similar to a bee sting. ### Why is this spider in my house? They enter buildings seeking shelter, dark hiding spots and prey (insects attracted to lights). Basements, garages and sheds are common indoor locations. ### How can I get rid of dark fishing spiders? Reduce insect prey by turning off unnecessary outdoor lights, seal cracks and gaps around windows and doors, remove clutter and webs, and use a vacuum to remove spiders and egg sacs. Use pesticide sprays only as a last resort and follow label instructions. ### Where does the dark fishing spider live? It is found in eastern and central North America, commonly at woodland edges, stone walls, rock piles, stream margins and around human structures. ### Will it come back after I remove it? Possibly—if habitat, shelter and prey remain available. Sealing entry points and reducing insect attraction helps prevent reappearance. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/82117), [Wikipedia](https://en.wikipedia.org/wiki/Dolomedes_tenebrosus). Identify insects and spiders from a photo with the Insect Scanner iPhone app: https://apps.apple.com/app/id1543946563?pt=126685406&ct=web-markdown&mt=8 Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.