American Nursery Web Spider
Pisaurina mira
Pisauridae (Nursery Web Spiders), Order Araneae
Physical Description
Elongated body shape with a distinct cephalothorax and abdomen. The cephalothorax is roughly oval and marked with distinct longitudinal stripes, while the abdomen is tapering and slightly flattened. The surface has a fine covering of hairs, giving it a somewhat matte texture. Females tend to be slightly larger and bulkier than males.
Size Estimate
Body length typically ranges from 13 to 20 mm for females and 10 to 15 mm for males, with a leg span reaching up to 50 to 75 mm.
Coloration & Markings
Variable base coloration ranging from light brown, tan, to grayish. Features a prominent darker median band running down the carapace, flanked by lighter stripes. The abdomen often displays a wavy, jagged-edged dark central stripe (cardiac mark) bordered by lighter lines.
Web Type
Does not build a traditional web to catch prey. Instead, females construct a specialized nursery web of silk spun around foliage or grass just prior to the hatching of their egg sacs.
Eye Arrangement
Eight eyes arranged in two slightly curved, recurved rows. The eyes are relatively uniform in size compared to wolf spiders, which helps distinguish the family Pisauridae.
Leg Characteristics
Long, robust legs featuring distinct dark banding or rings. Legs are held in a characteristic sprawling posture when at rest, and all four pairs are equipped with spines.
Venom & Safety Information
Venom Information
Contains mild neurotoxic venom used primarily to subdue insect prey. It is not considered potent or dangerous to humans.
Medical Significance
Harmless to humans. A bite may cause minor local pain, redness, or swelling similar to a mosquito bite, but medical attention is rarely required.
Safety Recommendations
No special precautions needed. If found inside a house, gently guide it into a container and release it outdoors. Avoid handling bare-handed if it is a brooding female.
Habitat & Behavior
Habitat & Range
Widely distributed across eastern and central North America. Prefers tall grasses, shrubs, low bushes, forest edges, and damp meadows near water sources.
Behavior & Temperament
An active nocturnal or crepuscular hunter that actively stalks prey rather than using a web. Generally docile toward humans, though brooding females can display defensive postures.
Diet & Prey
Carnivorous, feeding on a wide variety of insects including flies, beetles, grasshoppers, and occasionally small aquatic prey like tadpoles or small fish.
Seasonal Activity
Most active from spring through autumn, with mating occurring in late spring and early summer. Overwinters as immature juveniles under leaf litter or loose bark.
Description
The American Nursery Web Spider is a striking and agile hunter commonly encountered in grassy and shrubby habitats across North America. Known for its distinct marbled or striped patterns and remarkable maternal care—carrying its egg sac and building a silken nursery tent—it plays an important role in controlling insect populations.
Key Features
Elongated body, distinct longitudinal carapace stripes, uniform eye size relative to wolf spiders, and the habit of carrying egg sacs in the chelicerae.
Similar Species
Wolf spiders (Lycosidae), which look similar but carry their egg sacs attached to their spinnerets and typically have markedly enlarged posterior median eyes.
Life Cycle
Females carry their spherical egg sacs in their jaws until just before hatching, at which point they build a silken nursery tent. Young spiderlings stay within the web temporarily before dispersing.
Ecological Importance
Acts as an effective generalist predator, helping regulate insect populations in gardens, fields, and forest understories while serving as prey for birds and amphibians.
Conservation Status
Not evaluated by the IUCN, but populations are generally stable, widespread, and abundant throughout their natural range.
Interesting Facts
Male nursery web spiders often present potential mates with a nuptial gift—a wrapped prey item—to distract the female and avoid being cannibalized during mating.
Photography Tips
Use a macro lens with a fast shutter speed to capture details of the carapace stripes and leg banding. Shoot from a parallel angle to the spider for the best depth of field.
Identified: 2026-08-19T22:25:33.433400