American Nursery Web Spider
Pisaurina mira
Pisauridae (Nursery Web Spiders), Order Araneae
Physical Description
A medium-to-large spider with an elongated, slender cephalothorax and a tapering abdomen. They have a fine, velvety texture due to a dense covering of short hairs. In this specimen, the abdomen shows a distinct scalloped or wavy edge to the central dorsal band.
Size Estimate
Body length typically 10-19mm for females; leg span can reach 50-75mm (2-3 inches). This appears to be an adult or sub-adult female.
Coloration & Markings
Variable but usually tan, brown, or grey. This specimen features a prominent wide, dark brown median stripe with ivory or cream-colored scalloped margins along the length of the abdomen and cephalothorax.
Web Type
They do not use webs to catch prey; they are active hunters. However, females build a protective 'nursery web' in tall grass or foliage to house their egg sac just before the spiderlings hatch.
Eye Arrangement
Eight eyes arranged in two rows. The posterior row is slightly recurved (curving backwards), which distinguishes them from the straight or procurved rows of Wolf Spiders.
Leg Characteristics
Long, slender legs held in a characteristic 'X' pattern or with the front two pairs held close together when at rest. The legs are covered in fine spines and lack the heavy banding seen in some fishing spiders.
Venom & Safety Information
Venom Information
Possess a mild venom used to immobilize insect prey. It is not considered toxic to humans.
Medical Significance
Low medical significance. Bites are rare and usually result in only minor localized pain, redness, or swelling, comparable to a mild bee sting. No specialized treatment is typically required.
Safety Recommendations
Harmless to humans. If found indoors, they can be safely relocated using the 'cup and paper' method. They are beneficial residents of gardens and should be left alone to hunt pests.
Habitat & Behavior
Habitat & Range
Common across North America, particularly in the Eastern United States and Canada. Found in tall grass, shrubs, forest edges, and occasionally near human structures.
Behavior & Temperament
An active, diurnal and nocturnal ambush predator. They are generally shy and will flee rapidly if disturbed. They are not aggressive toward humans but can be defensive of their nursery webs.
Diet & Prey
Generalist predators that feed on a variety of insects, including flies, moths, and other spiders. They use their speed and agility rather than silk to capture prey.
Seasonal Activity
Most visible in late spring and throughout the summer. Adults are commonly found in May and June during the peak mating and nursery-building season.
Description
The American Nursery Web Spider is a master of camouflage and a devoted parent. Often seen resting on leaves with its front legs stretched forward together, it is a graceful and incredibly fast hunter that contributes significantly to garden pest control.
Key Features
Wide longitudinal dorsal band with scalloped white edges; legs held together in pairs; no distinct 'V' or 'hourglass' markings; two rows of eyes with the top row slightly curved.
Similar Species
Often confused with Wolf Spiders (Lycosidae), which have much larger primary eyes, and Fishing Spiders (Dolomedes), which are generally larger and more robust with different marking patterns.
Life Cycle
Females carry their globular egg sacs under their bodies using their chelicerae and pedipalps. Before hatching, she constructs a silk nursery. Lifespan is approximately one year, with maturity reached in late spring/early summer.
Ecological Importance
Serves as a vital biological control agent for insect populations in meadows and gardens. They also provide a food source for birds, wasps, and larger predatory insects.
Conservation Status
Not evaluated by IUCN, but considered common and stable throughout its range with no immediate threats.
Interesting Facts
The female is a dedicated mother, carrying her egg sac everywhere for weeks and then guarding the nursery until the spiderlings undergo their first molt. Males often present a 'nuptial gift' (a silk-wrapped insect) to the female to avoid being eaten during mating.
Photography Tips
Photograph from a top-down (dorsal) angle to capture the scalloped band pattern. A macro lens is helpful to show the eye arrangement, which is the definitive way to distinguish them from Wolf Spiders.
Identified: 2026-05-28T21:34:48.154967