The nursery web spider (family Pisauridae) is a widespread arachnid often encountered in gardens and grassy areas. These large, active hunters are frequently confused with ground-dwelling wolf spiders (Lycosidae) due to their similar appearance and roaming behavior. Unlike spiders that rely on sticky webs, the nursery web spider actively pursues or ambushes prey using keen vision and speed. Understanding their hunting method and size often leads to questions about the potential risk they pose to humans.
Safety Profile and Bite Specifics
The nursery web spider is not considered medically significant or a threat to human health. While all spiders are venomous, meaning they inject venom through a bite, the nursery web spider’s neurotoxic venom is weak. This venom is primarily effective only against the small insects, tadpoles, or fish they prey upon.
Bites from this species are rare because the spider is non-aggressive and prefers to flee when disturbed. A bite occurs almost exclusively as a defensive action, such as when the spider is accidentally squeezed or mishandled. If a bite does occur, the experience is typically mild, causing localized pain comparable to a pinprick or a mild bee sting.
Symptoms are usually transient, consisting of slight redness, minor swelling, or temporary discomfort at the site of injection. These localized effects resolve quickly without needing medical intervention beyond basic first aid, such as washing the area with soap and water. In extremely rare cases, an individual might experience a systemic allergic reaction to the venom, requiring immediate medical attention.
Key Features for Identification
Nursery web spiders are relatively large species with a distinct appearance. Females can reach a body length of 12 to 15 millimeters, with a substantial leg span that makes them appear even larger. Their body is robust, often described as velvety, featuring a cigar-shaped abdomen and long, strong legs.
Coloration is highly variable, ranging from pale gray or yellowish-orange to dark brown, often featuring a distinct pattern. A common marking is a darker longitudinal band running along the top of the cephalothorax and abdomen. When at rest, they often hold their front two pairs of legs rigidly outstretched and close together, which is a key identifying posture.
Nursery web spiders are often mistaken for wolf spiders because both are active hunters. However, they are differentiated by how the female carries her egg sac: the nursery web spider holds hers in her chelicerae (mouthparts). They are also distinguished from orb weavers because they do not construct sticky, wheel-shaped webs to capture prey.
Habitat and Unique Web Structure
Nursery web spiders are found across diverse environments, including grasslands, gardens, wooded edges, and areas near water. They are typically encountered among tall vegetation, such as shrubs or grasses, where they hunt or bask in the sun. Although primarily outdoor spiders, they may occasionally wander into human structures when seeking shelter during colder periods.
The name “nursery web spider” is derived from the unique, non-hunting structure built by the mother, demonstrating strong maternal instinct. The female carries her spherical egg sac with her jaws until the spiderlings are about to emerge. She then constructs a dense, tent-like silken structure, typically among foliage, known as the nursery web.
The mother places her egg sac inside this protective tent, standing guard outside until the young spiderlings have hatched and completed their first molt. This silken tent is solely for the protection of the offspring and is not used to catch food. After about a week in the nursery, the tiny spiderlings disperse into the environment.