American Nursery Web Spider
Pisaurina mira
Pisauridae (Nursery Web Spiders), Order Araneae
Physical Description
Elongated body with a somewhat flattened appearance, featuring a tapered, cigar-shaped abdomen and a distinct carapace. The cephalothorax is longer than it is wide, and the overall texture is finely covered in short hairs, giving it a matte appearance. The first two pairs of legs are held close together.
Size Estimate
Body length typically ranges from 13 to 20 millimeters for females and slightly smaller for males, with a substantial leg span of up to 50 to 75 millimeters.
Coloration & Markings
Variable coloration ranging from light brown, tan, to grey. Typically features a broad, dark median band running down the length of the carapace and abdomen, often bordered by lighter yellowish or white lines. Some individuals have dark spots or chevrons along the dorsal surface.
Web Type
Does not build a traditional web to catch prey. Instead, mature females construct a specialized nursery web or silken tent among folded leaves or tall grass just before the young hatch.
Eye Arrangement
Eight eyes arranged in two curved rows of four, with the eyes being relatively uniform in size compared to wolf spiders, which helps distinguish the family Pisauridae.
Leg Characteristics
Long, strong legs with prominent spines. The first and second pairs of legs are typically held parallel and close together when resting or walking, a characteristic posture for nursery web spiders.
Venom & Safety Information
Venom Information
Contains mild neurotoxic and proteolytic venom designed to immobilize small invertebrate prey. It is not considered dangerous or medically significant to humans.
Medical Significance
Harmless to humans. A bite is extremely rare, typically only occurring if the spider is trapped directly against the skin or heavily provoked while defending an egg sac. Symptoms are generally limited to mild, localized pain and minor swelling.
Safety Recommendations
No special safety measures are required as they are harmless and beneficial. If found indoors, they can be gently relocated outside using a cup and a piece of paper.
Habitat & Behavior
Habitat & Range
Found throughout the eastern and central United States and parts of southeastern Canada. Prefers tall grasses, shrubs, woodland edges, gardens, and sometimes the exterior walls of buildings.
Behavior & Temperament
Active hunters that rely on excellent eyesight and vibration sensing. They are generally non-aggressive, fleeing when disturbed rather than biting, though females fiercely guard their egg sacs and nursery webs.
Diet & Prey
Generalist predators feeding on a wide variety of insects, including flies, beetles, moths, and other small spiders. They ambush or chase down prey rather than using a sticky web.
Seasonal Activity
Most active during the spring and summer months, with mating peaking in late spring and nursery webs appearing in mid-to-late summer. They overwinter as juveniles or sub-adults under loose bark or leaf litter.
Description
The American Nursery Web Spider is a remarkable hunter often spotted roaming foliage, tree trunks, and the exterior of rural homes. Known for their characteristic habit of holding their front two pairs of legs tightly together, these agile spiders do not spin webs to catch food but instead actively stalk or ambush their prey. Their dedicated maternal care, where females carry their egg masses and later construct elaborate silken nurseries, makes them fascinating subjects for nature enthusiasts.
Key Features
Elongated abdomen, distinct broad central band on the carapace and abdomen, habit of holding the front two pairs of legs tightly together, and the absence of a prey-catching orb web.
Similar Species
Wolf spiders (Family Lycosidae), which also roam the ground and foliage without webs. Wolf spiders can be distinguished by their eye arrangement, specifically the large pair of posterior median eyes, and the fact that female wolf spiders carry their egg sacs attached to their spinnerets rather than in their jaws.
Life Cycle
Mating occurs in spring. Females carry their spherical egg sacs in their chelicerae until just before hatching, at which point they spin a silk nursery tent in vegetation, guard it until the spiderlings disperse, and then typically die.
Ecological Importance
Serves as an important natural controller of insect populations in gardens, forests, and agricultural fields, while also acting as a food source for birds, amphibians, and larger predators.
Conservation Status
Not evaluated by the IUCN, but populations are widespread, stable, and resilient to moderate habitat disturbance.
Interesting Facts
Male nursery web spiders often present potential mates with a nuptial gift, such as a wrapped insect, to distract the female from cannibalizing them during courtship.
Photography Tips
Use a macro lens and approach slowly to avoid startling them. Shoot from a side angle to capture the leg posture and dorsal markings clearly, and ensure natural or diffused lighting to highlight the fine hair texture.
Identified: 2026-10-17T23:28:34.053891