Nursery Web Spider

The nursery web spider, represented in much of eastern North America by Pisaurina mira, is a slender, fast-moving hunting spider closely related to the fishing spiders. Unlike orb weavers, it does not rely on a web to trap prey, instead actively stalking and pouncing on insects in grass and low vegetation. Its body is typically brown, gray, or tan, often with a pale stripe running down the center of the back.

The species gets its common name from a remarkable maternal behavior: rather than leaving her eggs unattended, the female carries her large, round egg sac beneath her body, gripped in her chelicerae (fangs) and supported by her pedipalps, as she moves through vegetation. Shortly before the eggs hatch, she constructs a silken "nursery" tent among leaves or grass stems, places the egg sac inside, and stands guard nearby until the spiderlings disperse.

Nursery web spiders are active hunters found in fields, meadows, and woodland edges, where they help control populations of flies, moths, and other small insects.

• Slender, elongated body, typically brown, tan, or gray, often with a pale central stripe down the back
• Long, thin legs adapted for both running and climbing vegetation
• Females often seen carrying a large, round, papery egg sac in their fangs
• No permanent web for prey capture, though a temporary nursery tent is built before eggs hatch
• Lookalikes: fishing spiders (larger, associated with water, similar body shape), wolf spiders (stockier build, carry egg sac attached to spinnerets rather than in fangs)

Widespread across the eastern and central United States and southern Canada, nursery web spiders are found in tall grass, meadows, woodland edges, and shrubby areas, generally away from open water, which distinguishes their habitat from the closely related fishing spiders.

This spider is an active, wandering hunter rather than a web-builder, relying on speed and stealth to ambush insects among grass and foliage rather than trapping them in silk. Diet consists of flies, moths, crickets, and other small arthropods encountered while hunting. The species' most distinctive behavior is maternal care: females carry their egg sac in their jaws for weeks, periodically basking to keep the eggs warm, before finally weaving a protective silk tent among vegetation just before the spiderlings emerge, guarding the nursery until the young disperse.

After mating, the female spins a large, spherical egg sac and carries it beneath her body, held by her fangs and palps, for several weeks. As hatching nears, she constructs a tent-like nursery web among leaves or grass stems, secures the egg sac inside, and stands guard nearby. Spiderlings hatch within the tent and remain together briefly before dispersing to hunt independently. The spiders mature over the course of a season, with most populations completing one generation per year and overwintering as eggs or juveniles.