White Banded Fishing (Dolomedes albineus)

Physical description and identification

Most people find a white banded fishing spider only when it moves. It sits head-down on a tree trunk with its legs drawn tight against the bark, and its mottled grey-green colouring matches lichen so precisely that the outline disappears. Once you have seen the white bar across its face, however, the species is unmistakable — no other large North American spider carries that mark.

Adults

• Size: females measure roughly 18–26 mm in body length, males about 14–18 mm. The sexes are closer in size than in most of the genus. With the legs extended a large female spans 60–75 mm.
• Colour: highly variable. Individuals range from pale grey and bark brown to a distinct mossy or lichen green, a colour few big spiders in the region show. Dark flecks and streaks break up the pattern further. The carapace is often clothed in whitish hairs with a darker central mark.
• The white band: a clean white or cream band crosses the clypeus — the face below the eyes — and continues over the chelicerae. It is the single most reliable field character and gives the species both its common and its scientific name.
• Head shape: the cephalic region, the front part of the carapace carrying the eyes, is noticeably raised above the rest of the body, giving the spider a high-browed profile in side view.
• Eyes: eight eyes in two rows of four with the rear row strongly curved backwards and none enlarged, the standard nursery web spider pattern and an immediate way to rule out wolf spiders.

Eggs and the egg sac

The female produces a large, pale spherical sac containing several hundred small round eggs. Like every member of the family she carries it clamped in her jaws, supported by her pedipalps, and cannot feed while she does so. The sac is usually carried on a trunk or among bark flakes rather than over water.

Spiderlings

Shortly before hatching the female fixes the sac to vegetation or bark and spins a dense nursery web around it, then stands guard alongside. The spiderlings emerge, moult once inside that shelter, and scatter afterwards, climbing away over bark or drifting off on short silk lines. Juveniles overwinter part-grown in bark crevices and under loose bark, and mature the following summer.

The web

This species builds no snare. The nursery web is a nursery and nothing more, and every meal is taken by ambush: the spider waits motionless on bark, senses an insect through vibration and touch, and lunges. Our guide to spider webs explains how differently the true snare builders make a living. Like the rest of the genus it is fully at home on water and will run across the surface or dive beneath it when alarmed, using the air trapped in its hair coat to breathe.

Where the white banded fishing spider lives

The species is a southeastern United States endemic, not a nationwide one as some older accounts claim. Its range runs from Virginia and Maryland south through the Carolinas, Georgia and Florida, west along the Gulf to Alabama, Mississippi, Louisiana and eastern Texas, and northwards up the Mississippi valley into Arkansas, Tennessee, Kentucky and southern Missouri and Illinois.

Within that range it is a spider of wet woodland. Bald cypress and tupelo swamps, bottomland hardwood forest, wooded river and creek banks and shaded lake margins are its typical habitat. It lives on the trunks themselves, usually within a short distance of standing water, and favours trees with rough, lichen-covered or moss-covered bark that matches its colouring. Because it is arboreal rather than shore-bound, it is the one member of the genus that people routinely meet at eye level rather than at their feet, sometimes on the boards of a cabin or a boat house that stands among the trees.

Are white banded fishing spiders venomous?

Yes, in the same sense as almost every spider: it uses venom to subdue the insects it catches. The venom has no medical significance for people or pets, there is no antivenom because none is required, and no case of serious injury has ever been attributed to the species. It belongs to a family with no dangerous members and is unrelated to the recluse and widow spiders that account for nearly all genuinely harmful spider bites in the United States.

Can white banded fishing spiders bite?

A white banded fishing spider can bite if it is handled, pinned or trapped against skin, but it almost never gets to that point. Its instinctive response to a large animal is to slide around the trunk out of sight, then to run, and if the tree overhangs water it will drop and swim. Bites are rare enough that reports are anecdotal.

What a bite produces is minor and local: a brief sharp pain, some redness, mild itching and occasionally a small raised bump, all settling within a few hours to a day. Wash the site with soap and water and apply a cold pack. Medical advice is only warranted if pain becomes severe, if swelling spreads well beyond the bite, if the wound later shows signs of infection, or if hives, dizziness or breathing difficulty appear — which would indicate an allergic reaction rather than any toxic effect of the venom.

Ecological importance and behavior of the white banded fishing spider

This is a nocturnal ambush predator that uses camouflage as its main weapon. It spends the day motionless on bark, legs pulled in, and becomes active after dark, working its way over trunks and low branches. Because it hunts on trees rather than on the water surface, its diet is dominated by terrestrial insects: moths, crickets, beetles, cockroaches, flies and the occasional smaller spider. Individuals living low on a trunk above water also take emerging aquatic insects, tadpoles and very small fish, the behaviour the genus is named for.

Camouflage and escape: the combination of a flattened posture, a raised cephalic region and lichen-toned colouring makes the spider close to invisible on the right tree. If it is spotted it moves around the trunk to keep the wood between itself and the threat. Startled individuals can leap clear of the bark and, over water, dive and remain submerged.

Natural predators: bark-foraging birds are the main threat by day, along with lizards, tree frogs and snakes at night. Spider-hunting wasps paralyse adults to provision their nests, and ants and parasitoid wasps attack the egg sacs and nursery webs.

Prey–predator dynamics: as a large nocturnal predator working the trunks of swamp forest, it exploits a layer that few other big spiders in the region occupy, and a healthy population keeps a steady pressure on night-flying insects. Its own value as prey ties the trees to the birds and reptiles above.

Seasonal behaviour: adults are found from late spring into autumn, with females carrying egg sacs through the summer. Juveniles overwinter under bark. Females probably live around two years in total, males considerably less.

Relationship with humans: harmless and beneficial. Nothing about the species justifies control measures. If one appears on a cabin wall, a glass and a piece of card will move it back to the nearest tree.

Similar spiders and how to tell them apart

Quick facts

Did you know?

• The epithet albineus comes from Latin albus, white, for the band across the face — the mark that identifies the species at a glance.
• Green pigmentation is rare among large North American spiders. The mossy-green form of this species evolved to match the lichen and algae that coat swamp-forest bark, and individuals on darker trees are correspondingly greyer.
• It is the clearest exception to the rule that fishing spiders live at the water's edge: this one lives above it, on the trunks, and comes down to the surface mainly to escape.
• Startled individuals can leap outright from a trunk, a useful trick when the alternative is to be picked off by a bird, and they will swim and dive if they land in water.
• Like all nursery web spiders, the female carries her egg sac in her jaws rather than dragging it behind her, which is why she goes hungry for the weeks she is carrying it.

In summary, the white banded fishing spider is a large, beautifully camouflaged tree-trunk hunter of southern swamp forest, harmless to people and easily identified by the white bar below its eyes. Learn that mark and the high-browed profile, and a spider that most visitors to a cypress swamp walk straight past becomes easy to find.