Fishing Spider

Fishing spiders, genus Dolomedes, are large, semi-aquatic hunting spiders found near ponds, streams, lakes, and slow-moving rivers throughout North America. They have a robust, hairy body typically mottled brown or gray, often with pale stripes or bands along the sides, and long, powerful legs that allow them to stand and move across the surface of water using surface tension.

Rather than building a web to catch prey, fishing spiders hunt by resting at the water's edge with their front legs touching the surface, detecting vibrations from insects, tadpoles, or small fish. When prey is detected, the spider darts across the water to seize it, sometimes even diving briefly below the surface to pursue prey or to escape predators, aided by a layer of fine hairs that traps air and allows brief underwater excursions.

As one of the largest spiders in North America by leg span, fishing spiders play a notable role in wetland and riparian ecosystems, feeding on aquatic and terrestrial insects and occasionally very small vertebrates.

• Large, robust, hairy body, typically brown or gray with mottled patterning and pale stripes along the body margins
• Long, thick legs proportioned for both walking on land and skating across water
• No web used for prey capture; often found resting at the water's edge or on floating vegetation
• Females may be seen carrying a large round egg sac in their fangs, similar to nursery web spiders
• Lookalikes: nursery web spiders (smaller, found away from water), wolf spiders (stockier, no water association)

Found throughout much of North America near freshwater habitats - the edges of ponds, lakes, slow streams, marshes, and swamps. Some species are also found in woodlands somewhat removed from open water, resting on tree bark or in leaf litter, though most remain closely tied to wetland margins.

Fishing spiders are ambush predators that hunt at the water's surface, detecting ripples and vibrations from struggling insects or small aquatic animals with sensitive leg hairs. They can run across the water's surface using surface tension, dive briefly underwater to capture prey or evade predators, and climb back out onto shore or vegetation to feed. Their diet includes aquatic and terrestrial insects, other spiders, and occasionally very small fish or tadpoles. They are solitary and generally avoid confrontation, retreating into water or vegetation when disturbed.

Females carry a large, spherical egg sac beneath their body in their fangs, much like nursery web spiders, until the eggs are nearly ready to hatch. At that point she constructs a nursery web among waterside vegetation, secures the egg sac within it, and guards the structure until spiderlings emerge and disperse. Juveniles hunt small prey near the water's edge as they grow through successive molts. Most species complete one generation per year, overwintering as juveniles or adults in sheltered sites near the water.