American Nursery Web Spider
Pisaurina mira
Pisauridae (Nursery Web Spiders), Order Araneae. They are known for carrying egg sacs in their chelicerae and building silk nurseries for their young.
Physical Description
A robust spider with a long, oval abdomen that tapers toward the rear. The cephalothorax is slender and prominent. The overall body has a soft, velvety texture due to fine hairs. Female specimens are typically larger and more bulky than males.
Size Estimate
Body length ranges from 12 to 19 mm for females and 9 to 15 mm for males. Including the leg span, they can reach 40 to 50 mm (approximately 2 inches).
Coloration & Markings
Variable but usually tan, light brown, or grayish. Most specimens feature a wide, dark brown longitudinal dorsal stripe that runs from the eyes back to the tip of the abdomen, bordered by thinner white or cream lines.
Web Type
They do not build capture webs for hunting; they are active hunters. However, females build a protective 'nursery web' in tall grass or foliage to house and protect their spiderlings after the eggs hatch.
Eye Arrangement
Eight eyes arranged in two rows. The posterior row is slightly recurved (curving backward), and the eyes are relatively equal in size compared to wolf spiders, which have two very large eyes.
Leg Characteristics
Long, agile legs with prominent spines. At rest, they often hold their first two pairs of legs together straight forward, creating a distinct four-point appearance (X-shape) when including the back legs.
Venom & Safety Information
Venom Information
Neurotoxic venom used to immobilize small insects. The venom is not considered medically significant to healthy humans.
Medical Significance
Low danger level. A bite may cause minor localized pain, redness, or swelling similar to a bee sting. They rarely bite unless physically handled or pressed against the skin.
Safety Recommendations
If found indoors, they can be easily relocated using a cup and a piece of paper. Since they are harmless 'wanderers,' no chemical control is necessary or recommended.
Habitat & Behavior
Habitat & Range
Common throughout Eastern North America, from Ontario down to Florida and west to the Great Plains. They prefer tall grass, shrubs, forest edges, and are frequently found on the exterior of houses or near gardens.
Behavior & Temperament
An active ambush hunter that roams through vegetation looking for prey. They are generally shy and will flee if disturbed. They are not aggressive toward humans but can be defensive of their nursery webs.
Diet & Prey
Generalist predators that eat a wide variety of insects, including flies, moths, and other small arthropods. They use their speed and agility to overpower prey rather than silk.
Seasonal Activity
Most active from late spring through late summer. They are often noticed in early summer when females are carrying egg sacs or building nurseries.
Description
An elegant, long-legged spider often seen sunning itself on leaves or exterior walls. It is easily identified by its characteristic resting posture and the central racing stripe along its back. It plays a vital role in natural pest control.
Key Features
Wide central brown stripe, long tapering abdomen, and the habit of resting with the front two pairs of legs held together.
Similar Species
Often confused with Wolf Spiders (Lycosidae), but nursery web spiders have a different eye arrangement and lack the two massive primary eyes. They also resemble Dolomedes (Fishing Spiders) but are generally smaller and more terrestrial.
Life Cycle
Mating occurs in spring and summer. Females carry a large round egg sac under their bodies. Just before hatching, she builds a nursery tent. Females are known for showing significant maternal care.
Ecological Importance
Critical for controlling populations of garden pests and flies. They serve as a food source for birds, wasps, and larger predatory insects, maintaining balance in the food web.
Conservation Status
Not evaluated by the IUCN, but common and widespread throughout its range with no major threats noted.
Interesting Facts
Male nursery web spiders often present a silk-wrapped fly as a 'nuptial gift' to the female to avoid being eaten during mating. Sometimes, males will even wrap a worthless object, like a seed, to trick the female.
Photography Tips
Capture the spider from a top-down (dorsal) angle to show the stripe and eye arrangement. Side views are excellent for showing the spines on the legs and the shape of the cephalothorax.
Identified: 2026-07-14T06:25:09.015498