Gray Wall Jumping (Menemerus bivittatus)
If you live anywhere warm and have ever watched a small flat grey spider hunting on a sunlit wall, you have almost certainly met Menemerus bivittatus. Originally an African species, the gray wall jumper now lives on buildings right around the tropical world. It spins no capture web, hunts entirely by eyesight, and leaps on a silk safety line that it anchors a moment before it jumps.
By Dr Richard J. Pearce (PhD)Published August 1, 2020Updated September 13, 2026✓ Reviewed by Dr. James Watuwa
In this guide
- Physical description and identification
- Where the gray wall jumping spider lives
- Are gray wall jumping spiders venomous?
- Can gray wall jumping spiders bite?
- Ecological importance and behavior of the gray wall jumping spider
- Similar spiders and how to tell them apart
- Quick facts
- Did you know?
- Frequently asked questions
Physical description and identification
The gray wall jumper is a flat, pale, hairy jumping spider built for life on vertical surfaces. It belongs to Menemerus, a large genus of wall-dwelling Salticidae clothed in dense, light-reflecting hairs, and was described in 1831 by the French naturalist Léon Dufour; the name bivittatus — two-banded — refers to the pair of dark stripes along the body. A point worth correcting up front: this is not a native American or Asian species. Menemerus bivittatus is African in origin and has been carried by shipping to virtually every warm region on Earth.
Adults
- Size: females are 7–10 mm (0.27–0.39 in) in body length; males are smaller and slimmer at about 5–7 mm (0.19–0.27 in) — a medium-sized jumping spider, noticeably bigger than a zebra jumper.
- Colour and pattern: the body is brown but so densely covered in greyish-white hairs that the living spider looks silvery in sunlight. Males carry a black stripe down the centre of the abdomen with brownish-white stripes either side, and black and white banding on the legs, chelicerae and carapace margins. Females are browner, the carapace marked with a pair of dark bands separated by white stripes, and the abdomen edged with thick dark bands on each side.
- Build: the giveaway is flatness. The body is markedly depressed from top to bottom, letting the spider press into shallow cracks in masonry and bark; females have a larger abdomen and carapace.
- Eyes and legs: eight eyes in four pairs — the two anterior median eyes large and forward-facing for the sharp image, the smaller side eyes wrapping around the head to detect movement through nearly a full circle (see spider eyes). Legs short and banded, the front pair thickened for display, the rear pair muscular for the leap.
Eggs and egg sac
The female builds a flattened, purse-shaped case of white silk tucked into a crack in a wall, behind a shutter or in a bark fissure, lays 25 to 40 eggs inside it and stays to guard them. Because these retreats sit in the crevices the adults shelter in, several egg cases can be found along one sunny wall.
Spiderlings
The young hatch about three weeks after laying. They resemble small females — the distinctive male markings appear only at the final moult — and stay near the maternal retreat briefly before spreading out along the same wall, hunting in the adult manner from the start and growing by a series of moults.
Hunting, and why there is no capture web
No jumping spider builds a snare, and the gray wall jumper is no exception. It walks over the surface in short bursts, scanning with its side eyes, swivelling to bring the big front eyes onto anything that moves, then crouches, touches its spinnerets to the wall to anchor a dragline, and jumps. The leap is hydraulic: spiders lack extensor muscles at some leg joints, so the spider drives body fluid into its rear legs under sudden pressure and they snap straight. The dragline is not optional — it catches the spider when a leap misses on a vertical wall, and works as a rudder in the air. Silk also makes the moulting chamber, the egg case and the overnight retreat, but never a trap. Our guide to spider webs explains what web-building families do instead.
Where the gray wall jumping spider lives
Menemerus bivittatus is native to Africa and is now genuinely pantropical. It travels easily in cargo, nursery stock and building materials, and because it needs nothing more than a sunny wall and a crack to sleep in, one mated female is enough to found a population.
In the Americas it is well established in Florida, Texas, Louisiana and Hawaii, and extends through the Caribbean, Mexico, Central America and into South America as far as Paraguay. It is also widespread in tropical Asia, including India, and on many Pacific and Indian Ocean islands. Cold winters set its northern limit.
The habitat is a warm, sunlit vertical surface: tree trunks and the outside of buildings above all — stucco, brick, painted render, fences, columns, window frames and shutters. It is one of the most consistently house-associated jumping spiders in the tropics, but lives on the outside of the building rather than inside it, hunting the flies and gnats that gather on warm walls and around outdoor lights. At night and in wet weather it retires into a silk cell in a crevice.
Are gray wall jumping spiders venomous?
Yes, in the sense that nearly every spider is venomous — the gray wall jumper uses venom to subdue the flies and gnats it catches. It is not medically significant to people or pets, and no serious reaction has ever been documented from this species or from any other member of the Salticidae. No antivenom exists for any jumping spider, because none is required.
The venom is adapted to insect nervous systems and delivered in a very small volume, and the chelicerae of a 7 mm spider are barely capable of penetrating human skin. Menemerus is unrelated to the groups that matter medically, the recluse spiders and the widow spiders.
Can gray wall jumping spiders bite?
They can, but it happens very rarely and only in self-defence. A gray wall jumper that notices an approaching hand turns to face it, backs off, and then either sidesteps into a crevice or drops away on its dragline. A bite requires the spider to be pressed against skin.
The outcome is minor: a brief sting comparable to a mosquito bite, a small red mark and occasionally slight itching, settling within a few hours. Wash the site with soap and water and use a cold pack if needed; no creams, home remedies or medical treatment are required. Seek advice only if redness and swelling spread well beyond the bite, which indicates an uncommon allergic response or an ordinary skin infection rather than the venom itself.
Telling it apart on the wall: if the small grey spider turns to look at you and moves in short deliberate hops, it is a jumping spider and it is harmless. A brown recluse has six eyes in three pairs, a plain tan body with a violin mark and long thin legs, and flees without ever facing you. House spiders sit in a tangled web in a corner; the gray wall jumper never sits in a web at all.
Ecological importance and behavior of the gray wall jumping spider
This is a diurnal hunter occupying a niche almost nothing else uses: the open, sun-baked face of a wall or tree trunk, where a web would be blown apart and where prey lands constantly. Flies, gnats, midges, mosquitoes, small moths, ants and leafhoppers all settle on warm vertical surfaces, and a population of gray wall jumpers works that surface all day — meaningful, free pest control around houses in the tropics.
Hunting ability: a notably bold predator for its size, it regularly takes insects with a bigger wingspan than its own body length, crane flies among them, then carries the prey into a crevice to feed out of sight of birds.
Courtship: visual, like all salticids. Males approach with the banded front legs raised and waving, the body held low and turned side-on to show the pattern, advancing and retreating in a rhythm the female watches with her main eyes. Disputes between rival males are usually settled by posturing.
Natural predators: birds, geckos and lizards hunting the same surfaces; mud-dauber and spider wasps, which paralyse salticids to provision nest cells; and larger spiders, including huntsman spiders on the same walls.
Prey-predator dynamics: the flat body is defensive as much as anything; a threatened spider slides sideways into a crack a bird cannot reach, or drops on its dragline and hangs clear until the danger passes.
Seasonal behaviour: in the tropics all stages occur year-round, with activity tracking sunshine rather than the calendar; at the cool margins of the range it falls away in winter. Individual lifespan is roughly a year.
Relationship with humans: harmless and useful. The species does not damage buildings, leaves no webbing, does not bite unprovoked and eats the flies that gather on the walls it lives on.
Similar spiders and how to tell them apart
| Spider | How it differs from the gray wall jumper |
|---|---|
| Menemerus semilimbatus | The Mediterranean counterpart and the closest look-alike: same flattened build and grey pelt, but greyer and less banded, and its range is southern Europe, North Africa and the Middle East rather than the tropics. |
| Other Menemerus species | Around seventy, mostly African, all flat hairy wall-dwellers; reliable separation needs adult genitalia. |
| Zebra jumping spider (Salticus scenicus) | Smaller at 5–7 mm, black with crisp white transverse bars rather than a grey pelt, and a temperate-zone wall spider of Europe and North America. |
| Pantropical jumping spider (Plexippus paykulli) | Shares the same walls and warm range and is often confused with it: larger and more robust, dark brown with a clean white central stripe and white spots at the rear of the abdomen. |
| Huntsman spiders (Sparassidae) | Also flat and also found on tropical walls, but far larger, with long crab-like legs held sideways, and active mainly at night. |
Quick facts
| Other names | Gray wall jumper, grey wall jumper. |
|---|---|
| Scientific name | Menemerus bivittatus (Dufour, 1831), family Salticidae. |
| Distribution | Native to Africa; established throughout the tropics and subtropics, including Florida, Texas, Louisiana, Hawaii, the Caribbean, Central and South America to Paraguay, and tropical Asia. |
| Habitat | Sunlit vertical surfaces: tree trunks, exterior walls, fences, columns, shutters and window frames. |
| Web | None for catching prey. Silk makes the dragline, the moulting chamber, the purse-shaped egg case and the night retreat. |
| Diet | Flies, gnats, midges, mosquitoes, small moths, ants and leafhoppers; occasionally prey larger than itself. |
| Eggs | 25–40 per case, hatching in about three weeks; the female guards the case. |
| Predators | Birds, geckos and lizards, mud-dauber and spider wasps, huntsman spiders and larger jumping spiders. |
| Lifespan | About one year; all stages present year-round in the tropics. |
| Danger to people | None of medical importance. Bites are rare and mosquito-like. |
Did you know?
- The specific name bivittatus means "two-banded" in Latin, for the pair of dark stripes that run the length of the body.
- For a spider of 7–10 mm it is a remarkably ambitious hunter, recorded taking crane flies with a wingspan far greater than its own body length.
- Jumping spiders have the finest spatial vision of any animal their size, sharper than a cat's. The main eyes are long tubes with a layered retina that the spider moves behind a fixed lens, scanning an image rather than taking it in at a glance.
- The leap is hydraulic: with no extensor muscles at certain leg joints, the spider pumps body fluid into its hind legs to make them snap straight — and always fixes a silk dragline first, which is what makes jumping on a vertical wall survivable.
In summary, the gray wall jumper is an African spider that has quietly colonised the sunny walls of the entire tropical world: harmless, useful around a house, and one of the easiest jumping spiders to watch at close range.
Frequently asked questions about the gray wall jumping spider
What does a gray wall jumping spider look like?
It is a flattened jumping spider whose brown body is covered in dense greyish-white hairs, so it reads as silvery grey in sunlight. Males have a black central stripe on the abdomen and black-and-white banding on the legs and carapace. Females are browner, larger and carry thick dark abdominal bands.
How big do gray wall jumping spiders get?
Adult females measure 7 to 10 mm in body length, about 0.27 to 0.39 inches. Males are smaller and slimmer at roughly 5 to 7 mm, about 0.19 to 0.27 inches. That makes the species a medium-sized jumping spider, larger than a zebra jumper but far smaller than a big Phidippus.
Are gray wall jumping spiders venomous to humans?
They carry venom for subduing insects, but it has no medical significance for people or pets, and no serious reaction has ever been recorded from the species. The dose is minute and the fangs of a 7 mm spider barely engage human skin. No antivenom exists because none is needed.
Do gray wall jumping spiders build webs?
No. Like all jumping spiders they build no capture web and hunt entirely by eyesight. Silk is still essential: a dragline is anchored before every jump, and silk is used for the moulting chamber, the purse-shaped egg case and the crevice retreat where the spider sleeps.
How do gray wall jumping spiders hunt?
They patrol sunlit walls and tree trunks during the day, detect movement with the small side eyes, swivel to inspect it with the two large forward eyes, then stalk in slow bursts. Within range they crouch, anchor a silk dragline to the surface and leap onto the prey.
How many eggs does a female gray wall jumper lay?
Between 25 and 40 in a single flattened, purse-shaped case of white silk, which she builds inside a crack in a wall or bark and then guards. The spiderlings hatch about three weeks after laying and look like small females; male markings only appear at the final moult.
Where are gray wall jumping spiders found?
The species is African in origin and now lives throughout the tropics and subtropics. In the Americas it is established in Florida, Texas, Louisiana and Hawaii, through the Caribbean and Central America and south to Paraguay, and it is widespread in tropical Asia and on many islands.
Can a gray wall jumping spider bite a person?
Only in self-defence, if it is pressed against skin. The bite is comparable to a mosquito bite: a brief sting, a small red mark, sometimes mild itching, gone within hours. Wash the area and apply a cold pack if it bothers you. No further treatment is needed.
Are gray wall jumping spiders dangerous to have on my house?
Not at all. They live on the outside of buildings, not inside them, leave no webbing to clean, damage nothing and spend the day eating the flies, gnats and mosquitoes that gather on warm walls and around outdoor lights. They are worth keeping rather than removing.
What is the difference between the gray wall jumper and the pantropical jumper?
Both live on tropical walls and are easily confused. The gray wall jumper is flat and clothed in pale grey hairs with fine banding. The pantropical jumping spider, Plexippus paykulli, is larger and darker brown with a bold white central stripe and white spots at the rear of the abdomen.
References
- World Spider Catalog (2026). Menemerus bivittatus (Dufour, 1831). Natural History Museum Bern. wsc.nmbe.ch/spec-data/37329/taxon
