Brush Legged Wolf (Schizocosa ocreata)

Physical description and identification

The brush legged wolf spider is a brown, grey-flecked wolf spider with a stocky body and moderately long legs, coloured to vanish against dead oak and maple leaves. It is not a large spider, and most people only spot one because it moved. The identification hangs almost entirely on the adult male's front legs.

Adults

• Size: females reach about 9–12 mm in body length, males about 7–9 mm, with the legs adding roughly as much again. The figure of 0.8 inches (20 mm) sometimes quoted overstates the species — that is the size of a Carolina wolf spider, not this one.
• Colour: brown to greyish brown with a darker carapace, a pale median band running back from behind the eyes, and a mottled abdomen that usually carries a dark heart mark and faint chevrons. Legs are banded in muted brown. Females are paler and plainer, males darker and more contrasty.
• The brushes: mature males grow a dense cuff of stiff black bristles on the tibia of each front leg, so the first pair look as though they have been dipped in soot. Females and juveniles have no tufts at all. The bristles are ornaments, not tools — they are raised and waved in courtship, not used in hunting.
• Eyes: the standard lycosid pattern of four small eyes in a bottom row, two large forward-facing eyes above them, and two more set high on the head. Those big eyes throw back a green shine in torchlight; see our guide to spider eyes.

Eggs and egg sac

The female builds a rounded silk sac holding roughly 100 eggs and fastens it to her spinnerets, then carries it with her, basking to warm it and defending it fiercely. She will not drop the sac to escape a threat, and a female that loses one may try to recover it.

Spiderlings

The mother opens the sac when the young are ready, and the spiderlings swarm onto her abdomen and ride there in a dense mat for about a week before scattering into the leaf litter. Accounts that have them disperse immediately after hatching skip this stage, one of the defining behaviours of the family. Juveniles grow through a series of moults and overwinter part-grown among the leaves.

Hunting instead of a web

Schizocosa ocreata builds no capture web. It walks the litter layer, detects prey by movement and by vibration carried through leaves and twigs, and rushes it down. Silk goes into the egg sac, a dragline and a thin retreat under bark. Crickets, small beetles, flies, springtails and other spiders make up the diet.

Where the brush legged wolf spider lives

The brush legged wolf spider is an eastern North American species. Its range runs from southern Ontario and the Great Lakes south to the Gulf states, and from the Atlantic coast west to the edge of the Great Plains. It is common through the Ohio and Mississippi valleys — Ohio, Indiana, Kentucky and Tennessee hold dense populations — and it reaches Texas and Oklahoma at the western margin.

Habitat is more specific than "forest". This is a spider of deciduous woodland with a deep, dry leaf litter layer: oak-hickory and beech-maple woods, wooded ravines, riverside forest and shaded suburban woodland edges. The litter matters for a reason beyond shelter — dead leaves transmit vibration well, and the male's courtship signal depends on that, so populations thin out on bare soil, sand or rock. Look among fallen leaves, under logs and along woodland trails rather than in open lawns or houses.

Are brush legged wolf spiders venomous?

Yes, in the way almost every spider is: venom delivered through a pair of fangs subdues crickets and other insect prey. It has no medical significance for people or pets. No antivenom exists for any wolf spider because none is needed, and no serious human illness has been attributed to Schizocosa.

The older claim that wolf spider bites cause rotting skin lesions has been abandoned by medical toxicologists. Verified wolf spider bites produce short-lived local pain and nothing more; wounds once blamed on them usually turn out to be bacterial infections.

Can brush legged wolf spiders bite?

They can, but they are not inclined to. A disturbed brush legged wolf spider runs, freezes, or raises its front legs in a bluff display. Bites happen when a spider is held in a closed hand, trapped in clothing, or when a female guarding an egg sac is picked up.

A bite gives a sharp pinprick, brief burning, and sometimes a small red bump with mild swelling that fades within a day or two. Wash the site with soap and water and use a cold pack for the sting. Get medical advice if the redness expands, if the area becomes hot and increasingly painful after a day or two — which suggests infection rather than venom — or if you show signs of an allergic reaction. Do not cut, burn or apply suction to a spider bite.

Ecological importance and behavior of the brush legged wolf spider

This is one of the best-studied spiders in North America, largely because of its courtship. A mature male follows a female's silk dragline, picks up the chemical traces she left on it, and begins a display that works on two channels at once: he raises and waves his brush-tipped front legs where she can see them, and he taps, bounces and stridulates so that pulses travel through the leaf litter to her legs. Either channel alone can persuade a receptive female; together they work far better, and males courting on a substrate that does not carry vibration lose much of their success. Females favour larger tufts and higher signalling rates, and because tuft size depends on how well a male fed as a juvenile, the ornament honestly advertises his condition.

Activity: adults are active in daylight and at dusk on the forest floor, and their eyeshine at night shows they forage after dark as well. The claim that they are purely diurnal, unlike other spiders, goes too far.

Natural predators: ground-foraging birds such as towhees and thrushes, toads, shrews, lizards, centipedes, ants and larger spiders. Spider wasps paralyse adults to provision their nests, and females occasionally eat courting males, though this is far from routine and depends on how hungry the female is. See also what eats spiders.

Seasonal cycle: the species is annual. Juveniles overwinter in the litter, mature in spring, and adult males court and die between April and midsummer. Females carry egg sacs through summer and the young are independent by autumn. The lifespan is about one year, not the one to two years sometimes quoted.

Relationship with humans: useful and harmless. A dense population removes large numbers of crickets, flies and other litter insects from a woodland or a shaded garden. These spiders do not colonise buildings and do not survive long indoors.

Similar spiders and how to tell them apart

Quick facts

Did you know?

• The species was described in 1844 by Nicholas Marcellus Hentz, the French-born naturalist who named much of the early American spider fauna.
• A male's leg brushes are a nutritional receipt. Males that fed well as juveniles grow bigger tufts, so females choosing the showiest partner are reading his childhood.
• The vibratory half of the courtship signal only travels well through dead leaves. Play the same display to a female on granite and her response drops sharply — the habitat itself is part of the mating system.
• Juvenile females that watch adult males courting can later prefer the phenotype they were exposed to — learned mate preference in an animal with a brain the size of a pinhead.

In summary, the brush legged wolf spider is a small, harmless woodland hunter with an outsized scientific reputation. Its black-brushed front legs and its habit of drumming out a courtship rhythm in the leaf litter make it one of the few spiders whose private life is genuinely worth kneeling down to watch.