Paraphidippus

Physical description and identification

Paraphidippus is a small genus of American jumping spiders holding about fourteen described species. The name says what it is: para, alongside, plus Phidippus, the big genus it was split from. Most of its species are Mexican and Central American and rarely photographed; the one everybody meets is the emerald jumping spider, Paraphidippus aurantius.

Next to a Phidippus the difference is clear once you have seen both. A Paraphidippus is longer, slimmer and slightly flattened rather than round and bulky, its legs look proportionally longer, and its chelicerae lack the strong metallic green iridescence that marks the larger genus.

Adults

• Size: roughly 6–13 mm in body length across the genus, with females larger than males. Older sources quote a flat average of about 9.5 mm, which is a fair figure for P. aurantius but hides real variation between species.
• Colour: variable, but usually dark with a covering of iridescent scales. In P. aurantius the abdomen is black overlaid with brilliant green or bronze scales, and — the single best field mark — a narrow pale band runs right round the margin of the abdomen, with matching pale stripes along the sides of the carapace. Males tend to be darker and more strongly contrasted; females are greener or browner with heavier patterning.
• Eyes: the standard salticid set of eight — an oversized forward-facing central pair, small side eyes for detecting motion, and a rear pair on the back corners of the carapace, together covering nearly a full circle. See our guide to spider eyes.
• Distinctive features: dense scales that flash green or copper as the angle of light changes, faintly banded legs, and swollen pedipalp tips in mature males. Species-level identification depends on adult genitalia, not colour.

Eggs and egg sacs

The female stitches a shelter, usually by folding a leaf and binding the edges with silk, lays a rounded mass of small eggs inside it and remains with them. She does not abandon the nest while the eggs develop, and she will defend it against ants and other small predators until the spiderlings emerge.

Spiderlings

Hatchlings are pale miniatures of the adult with fully functional principal eyes. They stay in the nest through the first moult, then leave to hunt prey their own size and build their own small silk retreats nearby. The iridescent scales develop gradually, so juveniles look far duller than mature spiders.

Hunting — no capture web

No member of the genus builds a snare. Silk is used for nests, egg sacs and draglines only. Hunting is done entirely by eye and in daylight, and this is where older accounts go wrong: Paraphidippus are diurnal, and they spend the night shut inside a silk retreat, not out hunting. The sequence is always the same — motion picked up by the side eyes, a turn to bring the target into the principal eyes, a slow stop-start stalk, a dragline anchored to the leaf, then a jump driven hydraulically by a surge of internal fluid pressure that straightens the hind legs. Claims that these spiders recognise shapes at four feet are also overstated: a spider this size identifies prey at a range measured in centimetres, which is still extraordinary. See our guide to spider webs.

Where Paraphidippus spiders live

The genus is confined to the Americas. Its range runs from the United States through Mexico and Central America — Guatemala, Honduras, Costa Rica — and into the Greater Antilles. Diversity is concentrated in Mexico and Central America; in the United States it is mainly a southern and southwestern presence, common in Texas and across the Gulf states, with P. aurantius reaching well up the eastern seaboard and into the Midwest.

These are foliage spiders. They hunt on the leaves and stems of shrubs, saplings, tall herbs and low tree branches, in woodland edges and clearings, along fence lines, in scrub and regularly in gardens and orchards. They favour partial sun, which is where their prey concentrates, and they retreat into a rolled leaf or a bark crevice at night and in bad weather. Unlike the wall-dwelling jumping spiders they are not house spiders and turn up indoors only by accident.

Are Paraphidippus spiders venomous?

Yes, in the way that almost all spiders are: they carry venom glands and use venom to subdue the insects they catch. It is not medically significant to humans or pets. There is no antivenom for any species in the genus because none has ever been required, no serious reaction has been documented, and the venom contains none of the tissue-damaging or neurotoxic components that make recluses and widows a medical matter. These are 1 cm spiders whose venom is a tool for handling flies.

Can Paraphidippus spiders bite?

They can, in the sense that any spider with fangs can, but it is rare and it requires the spider to be trapped against skin — caught in a glove, pressed inside a sleeve, or grabbed. Left alone, a Paraphidippus reacts to a hand by turning to look, backing off, and jumping clear on its dragline.

The outcome of a bite is a brief pinprick followed at most by a small itchy red mark that fades within a day. Wash with soap and water and leave it. See a doctor only if redness spreads or the area is still worsening after a couple of days, which indicates infection rather than venom. Suggestions that these bites can cause serious reactions in sensitive people go beyond the evidence.

Ecological importance and behavior of Paraphidippus spiders

Paraphidippus are solitary daytime hunters and useful generalist predators of the foliage layer. They take flies, small moths and butterflies, leafhoppers, plant bugs, caterpillars, small beetles and occasionally other spiders, working over the surface of leaves where many plant pests feed. Because they search actively instead of waiting in a web, they reach prey that no trap could intercept, which makes them a genuine part of the natural pest control of gardens, orchards and field margins.

Natural predators: birds and lizards take the biggest share, along with frogs, mantids, robber flies, predatory wasps, ants and centipedes. Nests and egg sacs are raided mainly by ants and parasitoid wasps. The spider's defences are camouflage against foliage, an explosive jump, and the dragline that lets it drop out of reach and climb straight back.

Prey-predator dynamics: some predation on these spiders is targeted and some incidental — a bird sweeping a branch takes whatever is on it. The spider's acuity is its best protection, since the eyes that judge a jump also register an approaching shadow in time to act.

Courtship and seasons: mating is preceded by a visual display. The male approaches in the female's line of sight, waves his raised front legs in a species-specific rhythm and edges sideways, retreating at once if she signals rejection. In the warmer parts of the range adults are present for much of the year; further north the population matures in late spring and summer and overwinters as juveniles in sealed silk retreats.

Relationship with humans: harmless and helpful. They cause no damage, do not colonise buildings, and remove insects from garden plants at no cost.

Species in the genus and similar spiders

Quick facts

Did you know?

• The genus was described in 1901 by Frederick Octavius Pickard-Cambridge, whose work on Central American spiders for the Biologia Centrali-Americana named a large share of the region's salticids.
• The name is a straight compound: para, "alongside", plus Phidippus, the genus it most resembles.
• The green of an emerald jumper is structural, produced by layered scales that scatter light, so the same spider looks brilliant green, bronze or almost black depending on the angle you view it from.
• The species name aurantius means "orange", which fits the reddish-gold sheen of some individuals far better than it fits the common name.
• Jumping spiders anchor a dragline before every leap and adjust its tension in mid-air, which is how a spider that jumps many times its own length still lands upright on a leaf.

In summary, Paraphidippus is a modest genus with one standout member. Look for a slim, scale-covered jumping spider on a leaf with a thin pale line running right round its abdomen, and you have found one — a completely harmless daytime hunter that earns its place in any garden.