Vampire (Evarcha culicivora)

Physical description and identification

The vampire spider is a small, hairy, sharp-eyed member of the jumping spider family, described for science only in 2003. One correction is needed before anything else: the species belongs to the genus Evarcha, a large salticid genus found across Africa, Europe and Asia. It is sometimes listed under Aptostichus, which is a completely unrelated group of North American trapdoor spiders and has nothing to do with this animal.

Adults

• Size: females measure roughly 4–7 mm in body length and males about 3–6 mm — a spider that sits comfortably on a fingernail.
• Colour: the sexes look strikingly different. Adult males have a dark body and a deep blood-red to rust-coloured face, set off by a band of white hairs above and below the front eyes that reads as an eyebrow. Females are a subdued grey-brown, mottled for camouflage, with some reddish tones around the eye region and pale markings on the abdomen.
• Eyes: eight eyes in the usual salticid layout — an enormous forward-facing central pair for detailed vision, small side eyes for detecting movement, and a rear pair on the back corners of the carapace. This gives near-complete visual coverage and the resolution the spider needs to recognise a mosquito by shape alone. See our guide to spider eyes.
• Distinctive features: the whole body is covered in fine hairs and scales. Males have swollen pedipalp tips, as in all mature male spiders, and use their contrasting faces in courtship display.

Eggs and egg sacs

The female lays her eggs inside a silk nest, wrapped in a sheet of white silk, and stays with them. Nests are built in sheltered spots — under a rock overhang, in a crevice on a wall, among dead leaves and grass stems — and are used for resting, moulting, mating and rearing as well as for the eggs.

Spiderlings

Juveniles look like small, drab versions of the female, with a grey-brown face; the red mask only appears when a male reaches maturity. What is remarkable is how early the specialised behaviour appears: juveniles barely a millimetre long already single out blood-fed mosquitoes, so the preference is inherited rather than learned. Growth proceeds through a series of moults carried out inside the silk nest.

Hunting — there is no capture web

The vampire spider builds no snare. Its silk goes into tube-shaped nests, often several together in loose aggregations, and into the dragline it trails behind it. Prey is caught in the open by sight. The spider spots a resting mosquito, turns to bring it into the principal eyes, and then works out a route — often an indirect one, approaching from behind or from the side rather than head-on. The final move is a jump powered hydraulically, by a surge of internal fluid pressure that straightens the hind legs, with the dragline anchored first as a safety line. For how this contrasts with the web-building families, see our guide to spider webs.

Where the vampire spider lives

Evarcha culicivora is known from a narrow band of country around Lake Victoria, in western Kenya and southern Uganda. Almost all research on the species has been carried out on the Kenyan lakeshore, and the spider becomes scarce a short distance inland.

Its habitat is tied directly to its prey. It lives on the outside walls of houses, on mud-brick and plaster, on rocks, fence posts, tree trunks and low vegetation — exactly the surfaces where mosquitoes rest after feeding. Human settlement is not incidental: the spiders are drawn to the smell of people, because that is where blood-fed mosquitoes accumulate. In this they behave like several other synanthropic salticids of the region, including the grey wall jumping spider and the pantropical jumping spider, both of which share the same sunlit wall surfaces.

Are vampire spiders venomous?

Yes, in the ordinary sense that applies to almost every spider: it injects a small quantity of venom to immobilise the insects it catches. The venom is tuned to mosquitoes and other small flies, and there is no evidence that it has any medically significant effect on humans, pets or livestock. No antivenom exists and none is needed. Despite the name, this spider has no adaptation whatsoever for feeding on vertebrates — the "vampire" in the name describes what it eats, not what it bites.

Can vampire spiders bite?

A vampire spider will not bite a person under normal circumstances, and with a body length of 4 to 7 mm its fangs are barely capable of penetrating human skin. The response to a hand is the standard salticid one: turn, watch, and jump away on a dragline. The only plausible bite is one delivered by a spider pressed against the skin, and the result would be a momentary pinprick with no lasting effect. Wash the spot and leave it alone; no first aid beyond that is warranted.

Ecological importance and behavior of the vampire spider

This is the only animal known to choose its prey on the basis of what that prey has recently eaten. Given a choice, Evarcha culicivora goes for female mosquitoes carrying a fresh blood meal, and within that it strongly prefers Anopheles — the genus that transmits malaria — over Culex. It picks them out using two independent channels: the distinctive head-down, abdomen-up resting posture of an Anopheles, recognisable by sight alone, and the odour of a blood-fed mosquito, detectable on its own in the dark. Either cue alone is enough.

Why blood matters: the blood is not only food. Spiders that have recently fed on blood-carrying mosquitoes become more attractive to the opposite sex, so a good meal feeds directly into mating success. Adults also drink plant nectar, which supplements the diet when mosquitoes are scarce and is now well documented in several jumping spiders.

Natural predators: larger jumping spiders — including Portia, the spider-hunting salticid that shares the same lakeshore habitat — along with mantids, predatory ants, wasps, geckos, lizards and small birds. Nests and egg sacs are raided by ants.

Prey-predator dynamics: hunting an insect that can fly away demands patience, and the spider's answer is a slow, indirect approach that keeps it out of the mosquito's line of retreat. Its acute vision does double duty, judging a jump and spotting an approaching predator. Nests are frequently clustered, and several spiders may occupy the same rock face or wall without conflict.

Relationship with humans: entirely positive, and of genuine research interest. By removing blood-fed female Anopheles before they can lay the next batch of eggs, the species is a candidate for supporting mosquito control in the Lake Victoria basin. It is important to be accurate here: no study has yet shown that these spiders measurably reduce malaria transmission, and they are not a substitute for bed nets, indoor spraying or medical care. What they demonstrably are is a harmless, highly effective local predator of the region's most dangerous insect.

Similar spiders and how to tell them apart

Quick facts

Did you know?

• The species name culicivora means "mosquito eater", from the Latin culex, a gnat or mosquito.
• It was described in 2003 by Wanda Wesolowska and Robert Jackson, and most of what is known about its behaviour comes from field and laboratory work at the Kenyan lakeshore.
• Juveniles only about a millimetre long already prefer blood-fed mosquitoes, which means the preference is hard-wired rather than learned by experience.
• The spiders can identify an Anopheles by its slanted resting posture alone, or by the smell of a blood meal alone — two separate cues that each work without the other.
• A spider that has recently eaten blood-fed mosquitoes becomes more attractive to potential mates, one of the few documented cases of diet directly shaping sexual attractiveness in a spider.
• Vampire spiders are drawn to human body odour — not because people are prey, but because people attract the mosquitoes that are.

In summary, the vampire spider is a 5 mm hunter with a very specific taste, and one of the most striking examples of prey specialisation known in spiders. It is harmless to people, useful to have on a wall, and a reminder that the most interesting animal in a village is not always the largest one.