Phidippus

Physical description and identification

Phidippus is a genus of large, heavily built jumping spiders (family Salticidae) centred on North America. About seventy-five species are currently recognised — older articles say sixty, a figure that predates the 2004 revision of the genus — and they include the most familiar jumping spiders on the continent: the bold jumper, the regal jumper and the red-backed jumper.

The most useful field mark for the genus is the chelicerae. In good light the fang bases of a Phidippus glow metallic green, blue-green or violet — a colour produced by the structure of the cuticle rather than by pigment. Very few other North American spiders show this so consistently.

Adults

• Size: body length runs from about 6 mm in the smallest species to around 22 mm in a well-fed female P. regius, which makes the regal jumper the largest jumping spider in eastern North America. Females are larger and much heavier-bodied than males in every species.
• Colour: extremely variable. Ground colour is usually black, grey or brown, overlaid with dense scales that can be white, cream, orange, scarlet or iridescent green. The abdomen normally carries a pale central band or triangle plus two or three pairs of spots. Juveniles are frequently orange where the adult is white, so colour alone is a poor guide to species.
• Eyes: eight eyes in the classic salticid arrangement — a huge forward-facing central pair flanked by smaller eyes, with a further pair set far back on the carapace. Between them they cover almost a full circle, and the principal pair delivers the sharpest image known in any animal this small. See our guide to spider eyes.
• Distinctive features: a dense fur of hairs and scales, short thick legs with conspicuous bristles, and tufts of pale hairs above the eyes in species such as P. mystaceus. Mature males have swollen, boxing-glove pedipalps.

Eggs and egg sacs

The female builds a thick silk nest under bark, a stone or a leaf curled and stitched shut, and lays her eggs inside it. Eggs are pale, oval and laid in a single mass; a large P. clarus female may produce well over a hundred. She seals herself in with them, stops feeding and guards the sac until the young emerge.

Spiderlings

Hatchlings remain inside the nest through their first moult, living on stored yolk, and disperse only once their fangs and eyes are fully functional. They leave over a period of days and immediately begin hunting prey their own size. Growth to maturity takes several moults and usually spans a full season.

Hunting — no capture web

No Phidippus builds a web to trap prey. Silk is used for the nest, the egg sac and the dragline, never as a snare. Hunting is a stalk: the spider picks up movement with its side eyes, pivots to bring the target into the principal eyes, creeps closer in stop-start bursts, fixes a dragline and jumps. The leap is powered hydraulically — a rapid rise in internal fluid pressure straightens the hind legs — which is why a spider with no bulky leg muscles can cover many times its body length. See our guide to spider webs.

Where Phidippus spiders live

The genus is essentially North American, with species from southern Canada through the United States and Mexico into Central America and the Greater Antilles. Diversity peaks in the southern and southwestern states; Florida alone holds a long list of species. A few have travelled with people — the bold jumper is established in Hawaii and has turned up in the Netherlands and on Pacific islands.

Older accounts describe the genus as restricted to open grassland. That is too narrow. Phidippus species occupy old fields and prairie, but also forest edges and tree trunks, chaparral, desert scrub, coastal dunes, orchards, crop fields, gardens, fences and the sunny outside walls of houses. What they need is a sunlit surface with cover close by and plenty of insect traffic. Arboreal species such as P. otiosus and the regal jumper are found on trunks and palm fronds; ground species hunt in litter and low herbs.

Are Phidippus spiders venomous?

Yes, like nearly all spiders, and for the same reason: venom is how they subdue insect prey that is often as large as they are. What matters medically is that Phidippus venom is not dangerous to people. No antivenom exists for any species because none has ever been needed, no death has been attributed to the genus, and there is no tissue-destroying component of the sort found in recluse venom or the powerful nerve toxin of the widows. These are large spiders with proportionally large fangs, so the mechanical bite can genuinely hurt — but that is puncture pain, not envenomation of consequence.

Can Phidippus spiders bite?

They can, and of all the jumping spiders they are the ones most likely to manage it, simply because a 15 mm female has fangs long enough to break skin. Even so, bites are uncommon: a Phidippus confronted by a hand will normally watch, back away, then jump clear on its dragline. Most recorded bites involve a spider trapped inside clothing or bedding, or one picked up and squeezed.

The usual result is a sharp sting at the moment of the bite, followed by a small red swollen area, sometimes itchy, that settles over a day or two. Wash the site with soap and water, apply a cold pack and take an ordinary painkiller if needed. Seek medical advice if redness spreads, pus develops or the area is still worsening after 48 hours — that points to a skin infection rather than the venom. Do not apply heat, suction or home remedies.

Ecological importance and behavior of Phidippus spiders

Phidippus are daytime hunters and generalist predators, and in farmland they matter. They take flies, moths, caterpillars, leafhoppers, plant bugs, beetles, grasshopper nymphs, ants and other spiders, and because they actively search rather than wait for prey to arrive, they reach pests that web-builders never encounter. Studies of cotton, alfalfa and orchard systems repeatedly list Phidippus among the most abundant hunting spiders on the crop.

Natural predators: birds are the main threat, along with lizards, mantids, robber flies, wasps in the families Pompilidae and Sphecidae, ants and larger spiders such as wolf spiders. The nest is raided by ants and parasitoid wasps. A cornered Phidippus raises its front legs in a threat display, and several species appear to gain protection from mimicking or resembling stinging insects.

Prey-predator dynamics: excellent vision cuts both ways. The same acuity that lets a spider recognise a fly at several body lengths also lets it recognise an approaching bird, and the standard escape is a sideways jump onto a dragline. Because they identify what they are looking at before committing, Phidippus avoid chemically defended prey such as ants far more reliably than web-builders can.

Courtship and seasons: males court visually, approaching with the front legs raised, waving them in a fixed rhythm, dipping and side-stepping, and drumming vibrations into the surface the female stands on; an unreceptive female drives him off. In most of the range adults mature in late spring, breed through summer, and the population overwinters as part-grown juveniles sealed in silk nests under bark or in leaf litter. Most individuals live about a year.

Relationship with humans: beneficial and famously charismatic. They do not infest houses and damage nothing, and they are the spiders most often kept and photographed by enthusiasts because they are curious rather than fearful. A wanderer indoors can be scooped into a cup and put back outside.

Species in the genus and similar spiders

Quick facts

Did you know?

• The metallic green of a Phidippus's fang bases is a structural colour, produced by layered cuticle that interferes with light — the same physics that colours a beetle's shell, not a pigment.
• The genus name comes from Greek roots meaning "sparing of horses", and echoes a classical Phidippus who served as physician to Deiotarus, king of the Celtic Galatians.
• Jumping spiders see more colour than was long assumed: some salticids have photoreceptors sensitive into the ultraviolet, and males signal with patches that reflect it.
• The dragline is always laid before the jump. Slow-motion footage shows the spider tensioning the line in mid-flight to control its pitch and land the right way up.

In summary, Phidippus is the genus that makes people like spiders: big, colourful, sharp-eyed, harmless, and busy eating the insects that damage crops and gardens. Learn the iridescent chelicerae and you can name the genus from a photograph, even when the colours of the individual species refuse to cooperate.