Apache Jumping (Phidippus apacheanus)

Physical description and identification

The Apache jumping spider is one of the boldest-coloured spiders in North America: a stout, hairy salticid whose upper surface is coated in orange to scarlet scales while the legs and flanks are glossy black. It sits high on stems and stalks in dry, open country and rarely tries to hide, which makes sense for an animal that is advertising rather than concealing itself. Like all Phidippus, it has the squared carapace, the heavy front legs and the pivoting, attentive posture of a visual hunter.

Adults

• Size: females are large, roughly 10–18 mm (0.4–0.7 in) in body length; males are smaller and slimmer at about 7–12 mm. Widely copied figures of a 22 mm female and a 3.3 mm male are unreliable — the male measurement in particular is far too small for any adult Phidippus and appears to be a transcription error. The sexes differ in size, but not dramatically so.
• Color: females carry orange to orange-red scales over the abdomen and cephalothorax, black on the undersides, and black legs that often show paler orange or reddish rings at the joints. Males are more uniform, with dense scarlet scales on the abdomen and carapace and the rest of the body and legs glossy black. Both sexes fade to brick or rust as the scales wear.
• Eyes: eight eyes in four pairs. Two enormous anterior median eyes face forward and deliver the acuity the spider hunts with, while the smaller lateral and posterior pairs give near-panoramic motion detection. That arrangement separates it at once from a red crab spider or a juvenile wolf spider; see our guide to spider eyes.
• Distinctive features: the chelicerae are iridescent, flashing green or blue against the red body. Males have fringed front legs and swollen pedipalps. Many individuals show faint bands or spots within the red field of the abdomen, and the legs are notably hairy.

Eggs and egg sac

The female builds a dense silk retreat in rolled grass, among leaf bases, under a stone or in a crevice, lays her eggs inside it in a papery sac, and then guards them closely, feeding little until they hatch. The retreat is sealed, which is why egg sacs of this species are almost never found in the open.

Spiderlings

Spiderlings hatch mainly in spring and summer. They stay in the maternal retreat through their first moult and then disperse. Young spiders resemble the female in colour, with orange tones on the abdomen and cephalothorax and legs that look distinctly paler than the body; the adult contrast between red scales and black legs develops over the final moults. Growth proceeds through a series of moults, described in our guide to spider moulting.

Hunting and the use of silk

The Apache jumping spider builds no capture web. Its hunting is entirely visual: the side eyes register movement, the spider rotates to bring the big forward eyes on target, measures the distance, stalks and leaps. Silk has three uses — a dragline anchored to the substrate before each jump, which works as a safety rope and lets the spider correct its body angle in mid-air; a tent-like retreat for moulting, night-time rest and shelter from heat and rain; and the egg sac. Accounts describing the tent-like retreat as a device for catching prey are mistaken: nothing is ever trapped in it, and the structure has nothing in common with a spider web spun by an orb weaver.

Where the Apache jumping spider lives

Phidippus apacheanus is a spider of warm, dry, open country across the southern United States and Mexico. It is common through the Southwest — Arizona, New Mexico, southern California, Texas and Oklahoma — and the range extends east across the southern plains and the Gulf states into the sandhills and dry flatwoods of Florida. Older popular lists that add Cuba are not supported by current taxonomic catalogues, which give the distribution as the United States and Mexico.

Within that range it favours sunny, sparsely vegetated ground: desert and semi-desert scrub, dry grassland and prairie, chaparral, sandhills, roadsides, old fields and the edges of agricultural land. It hunts on grass stems, yucca and agave, low shrubs and tall herbaceous plants, and often perches conspicuously at the top of a stalk. It does not colonise buildings and is not a house spider.

Are Apache jumping spiders venomous?

Yes, in the ordinary sense in which nearly all spiders are: the Apache jumping spider injects venom to subdue the insects it catches. It poses no medical risk to people or pets. Jumping spider venom acts on small arthropods and contains neither the tissue-destroying enzymes of the recluse spiders nor the vertebrate-active neurotoxins of the widow spiders; no member of the family Salticidae is regarded as medically significant anywhere in the world. The one real exception is an individual allergy to arthropod proteins, which reflects the person rather than the spider. The vivid red colour signals a sting the spider does not actually possess.

Can an Apache jumping spider bite?

It can. A large female is easily big enough to pierce skin, but bites are rare and strictly defensive: the spider must be pressed, squeezed in clothing or gripped. Left alone it turns to watch an approaching hand, backs off and then runs or drops away on its dragline.

A bite feels like a pinprick and leaves a small red mark with brief soreness or itching, usually gone within a few hours. Wash with soap and water, apply a cold pack and leave it. Seek medical advice only if redness spreads, swelling is out of proportion, or there are allergic signs such as hives, dizziness or difficulty breathing.

Ecological importance and behavior of the Apache jumping spider

This is a day-active visual predator of open arid habitats, taking flies, small moths, grasshopper nymphs, leafhoppers, plant bugs, beetles, ants and other spiders; a large female will tackle prey approaching her own size. In dry rangeland, where aerial webs are scarce for want of anchor points, sight-hunting spiders do much of the invertebrate predation.

Mimicry: the red-and-black pattern copies female velvet ants of the genus Dasymutilla, flightless mutillid wasps whose sting is severe enough that birds, lizards and small mammals learn to avoid the colour scheme. The spider is harmless, so this is Batesian mimicry — a defenceless species profiting from a dangerous model's reputation. The eastern cardinal jumping spider and several other warm-country Phidippus run the same bluff.

How the jump works: spiders have no extensor muscles in the leg joints that matter for leaping. The spider raises its internal blood pressure and forces the hind legs straight, so the jump is hydraulic, covers several body lengths, and is always preceded by the anchoring of a dragline that serves as brake and tether.

Natural predators: insectivorous birds, lizards, toads and frogs, larger spiders, and mud-dauber and spider-hunting wasps that paralyse spiders to provision their nests; parasitoid wasps attack the egg sacs.

Relationship with humans: entirely benign and quietly useful in gardens, fields and rangeland. There is no reason to control it, and an individual found indoors can be carried out on a sheet of paper.

Similar spiders and how to tell them apart

Quick facts

Did you know?

• The mimicry runs in both directions of the colour range: some populations are closer to orange and others to deep scarlet, matching the local Dasymutilla species, which themselves form large mimicry rings across the American Southwest.
• The spider's silk retreat is a bedroom, not a trap. Jumping spiders spend the night, every moult and much of the hottest part of the day inside it, and a female will spend weeks sealed in with her egg sac.
• Jumping spiders swivel their retinas rather than their eyes. Muscles inside the head move the tube-shaped retina of each big front eye from side to side, so the spider can study an object without moving a leg.
• Salticidae is the largest spider family on Earth, with well over 6,000 described species — browse the group on our jumping spiders page, from the regal jumping spider to the zebra jumper.

In summary, the Apache jumping spider is a harmless, superbly sighted hunter of dry open country whose alarming colours are a borrowed costume. The wasp it imitates is worth respecting; the spider is worth watching.