Is the nursery web spider dangerous?

The nursery web spider is harmless to people. Harmless. No medical significance.

How do you identify a nursery web spider?

Carries a large round egg sac held in the jaws beneath the body. Broad dark stripe down the back with pale edges.

Where do nursery web spiders live?

The nursery web spider is found across most of the United States, in habitats including grassland, garden and woods.

Nursery Web Spider

Harmless

Pisaurina mira

The nursery web spider is a common grassland hunter that carries its egg sac in its jaws — a habit that separates it immediately from wolf spiders, which drag theirs behind. Shortly before the eggs hatch the female builds a silk tent around them and stands guard until the young disperse.

Bite risk: Harmless. No medical significance.
Size: Body 10–17 mm. Body about a thumbnail with long legs held in pairs.
Appearance: Slender tan or straw-coloured body with a broad dark stripe running the length of the back, edged in cream. The long legs are usually held in pairs, pointing forwards and backwards along a grass stem.
Web: No catching web. The female builds a tented nursery web around her egg sac in vegetation and guards it.
Found in: grassland, garden, woods
Family: Pisauridae
Range: Most of the United States

How to identify a nursery web spider

Carries a large round egg sac held in the jaws beneath the body.
Broad dark stripe down the back with pale edges.
Legs held in pairs alongside a stem when at rest.
No catching web.

How it behaves

Ambush hunter in low vegetation. Females guard the nursery web fiercely against insects, and flee from people.

What the nursery web spider is confused with

One observation settles each of these.

Wolf spider →

Wolf spiders drag the egg sac behind, attached to the spinnerets. Nursery web spiders carry it in the jaws.

If you think you were bitten

Most suspected spider bites are not spider bites. Studies of patients presenting with a “spider bite” repeatedly find that the large majority are bacterial skin infections — frequently MRSA — which need antibiotics rather than reassurance. A spreading, painful, pus-filled sore is far more likely to be an infection than a spider.
Wash it, ice it, and watch it. Clean the area with soap and water, apply a cold pack, and keep an eye on it.
Get medical care if the wound spreads or darkens, if you develop cramping, sweating, fever or severe abdominal pain, or if you are confident it was a widow or a recluse.
Bring the spider only if it is already dead and to hand. Do not go looking for it. Doctors treat symptoms, not species.

In the US, the Poison Help line is 1-800-222-1222. This site is a reference, not medical advice.

Not sure it was a nursery web spider? Identify it step by step →