Salticus

Physical description and identification

Salticus is the genus that named the family. The Latin saltus means a leap, and when Latreille erected the genus in 1804 he gave that name to the small striped spiders everyone had watched jumping on garden walls. All six thousand or so jumping spiders known today carry the family name Salticidae because of it. Around forty-five to fifty species are described, the count shifting as Mediterranean and Central Asian material is revised.

Adults

• Size: small. Body length runs roughly 4–7 mm, with females a little larger and heavier than males. The zebra spider (Salticus scenicus), the reference species, has females of about 5–7 mm and males of about 5–6 mm.
• Colour: black or dark brown with white or cream bands of flattened scales — a pale stripe around the front of the carapace and two or three pale bars across the abdomen, which is the striped effect the common name refers to. The scales wear thin with age, so old individuals look duller.
• Eyes: eight, with an enormous forward-facing pair dominating a flat face, a small pair beside them and two further pairs set back for near all-round detection of movement. The principal eyes have narrow retinas on movable stalks, so the spider scans an object rather than seeing it at once — see spider eyes.
• Distinctive features: adult males have greatly enlarged chelicerae that project forward like tusks. They are not defensive weapons; males use them in head-to-head shoving contests with rivals and to hold the female's fangs during mating. Legs are short, banded and strong, with the front pair noticeably thicker.

Eggs and egg sacs

The female spins a silk chamber in a crevice — under a stone, a flake of bark, a roof tile or a window frame — and lays a small clutch inside it, commonly five to fifteen eggs wrapped in a soft sac. She seals herself in and guards it until the spiderlings emerge.

Spiderlings

Spiderlings are pale and unbanded at first and take on the pattern over successive moults, each inside a fresh silk chamber. They disperse within days of leaving the nest, often on drifting silk, and a sunny wall can carry a remarkable density of juveniles by midsummer.

Hunting, and what the silk is for

No Salticus builds a capture web. The spider crosses a wall in short runs, stops, turns to face anything that moves, and if it resolves as prey begins a stalk that ends in a jump of several body lengths. The leap is hydraulic rather than muscular — blood pressure straightens the hind legs — and a dragline is anchored first, so a miss leaves the spider hanging instead of falling off the wall. Silk otherwise builds the resting, moulting, egg and winter chambers. See our guide to spider webs.

Where Salticus spiders live

The genus is essentially Holarctic, centred on Europe, North Africa and temperate Asia, with a handful of species in North America and a distinctive group of endemics in the Canary Islands. Salticus scenicus is the widest-ranging: it occurs throughout the United Kingdom and continental Europe, across Russia to the Pacific, and through much of the northern United States and southern Canada.

Older accounts list the range as a scatter of countries from South Africa to Brazil. That is misleading: a few species do occur around the Mediterranean margin and in Central Asia, but the genus as a whole is a northern, temperate one and is not a tropical group.

Habitat is remarkably consistent: a sunlit vertical surface. House and garden walls, fences, gateposts, window sills and greenhouse frames are the classic sites, with rocks, quarry faces and tree trunks in wilder settings. S. cingulatus is the tree-trunk specialist and lives in woodland rather than on buildings. All need direct sun, and they vanish the moment a wall falls into shade.

Are Salticus spiders venomous?

Yes, in the way nearly every spider is. Salticus species inject a small dose of insect-specific venom to subdue the flies, midges, aphids, small moths and other spiders they catch.

It carries no medical significance for people. There is no antivenom for any jumping spider anywhere in the world because none has ever been needed, and no death or serious systemic illness has been attributed to the family Salticidae. These are also very small spiders, with fangs that in most cases struggle to break human skin at all.

Can Salticus spiders bite?

Only in principle. A Salticus weighs a fraction of a gram, and its first reaction to a hand is to turn, watch and jump sideways out of reach. A bite would require the spider to be held or pressed against skin, and even people who photograph them constantly rarely report one.

If one occurred the effect would be a faint pinprick with perhaps a pinhead of redness, gone within an hour or two. There is no blistering and no lasting mark. Wash the area with soap and water. Only a genuine allergic reaction — spreading hives, swelling away from the site, difficulty breathing — warrants medical attention, and that is a response to the bite rather than to any toxin.

Ecological importance and behavior of Salticus spiders

Salticus spiders are strictly diurnal and tied to sunshine, which is why they appear on a wall the moment light hits it. Hunting is visual: the spider detects movement with its side eyes, pivots to bring the target into the principal eyes, assesses it, then stalks. Prey includes flies, midges, mosquitoes, aphids, small moths, ants and other spiders, sometimes close to its own size.

Natural predators: birds, lizards, mantises, larger spiders and mud-dauber and spider-hunting wasps that paralyse salticids to provision their nests. Parasitoid wasps attack the eggs inside the retreat.

Prey-predator dynamics: a sunny wall is a hunting ground almost no other spider works in daylight, so Salticus takes a share of the insect fauna that web builders and night hunters never reach — around houses, a steady removal of flies and midges all summer.

Courtship and seasonal behaviour: courtship is a visual performance. The male approaches with his front legs raised and spread, waving them in a zigzag while moving from side to side, and because both sexes see well the whole display is staged for the female's eyes. Rival males meet face to face with their long chelicerae locked and push until one gives way, and the larger male almost always wins without injury. In temperate climates the cycle is annual: juveniles overwinter in silk chambers under bark, stones and window frames, mature in spring, breed in late spring and early summer, and the adults die off by autumn. A claim that these spiders live two to three years belongs to larger, longer-lived species and not to this genus.

Relationship with humans: uniformly positive. They live on the outside of buildings, eat nuisance flies, damage nothing and cannot harm anyone. They are also the easiest wild spiders to observe, because a zebra spider will readily turn and watch a person watching it.

Species in the genus and similar spiders

Quick facts

Did you know?

• The family name Salticidae comes from this genus, and the genus name from Latin saltus, a leap. Every jumping spider in the world is named, indirectly, after the little striped spider on the garden wall.
• Naming the genus was not tidy. Latreille established Salticus in 1804; Walckenaer proposed Attus for much the same spiders the following year and went on using his own name, and the priority of Salticus was only fully settled by later cataloguers.
• The zebra spider is a mainstay of vision research: experiments on how salticids judge distance, plan detours around obstacles and recognise prey have used Salticus scenicus for over a century.
• The male's tusk-like chelicerae are for rivals, not for people. Two males lock fangs and push, and the contest is usually decided by size alone.
• They can jump many times their own body length, but never without insurance: the dragline is attached first, every time.

In summary, Salticus is a small, harmless, sharp-eyed genus that most people in the northern hemisphere have met without knowing its name. The black-and-white bands, the stop-start walk and the habit of turning to look straight back at you identify it on sight — and it is the spider the whole jumping spider family is named after.