40 Fun Facts About Black Widow Spider

Black widow spider venom is reported to be 15 times stronger than the venom of which snake?

Rattlesnake venom is the famous comparison, yet most people bitten by a black widow suffer no serious damage. The spider is not aggressive and bites only in self-defence.

Early medical reports of black widow spider bites often described men bitten while using what?

Outhouses were ideal hiding places for the spiders, and the genitals were often where the bite landed. No lasting injury to the area was reported.

Weight for weight, the silk of the western black widow spider is famously compared with wire made of which metal?

Steel wire only matches the silk at equal thickness. Because the metal is about six times denser, a thread of widow silk is far stronger than a wire of the same weight.

The 'widow' in black widow spider refers to what the female sometimes does to a male after mating?

She devours him far less often than the legend suggests. Much of the evidence comes from laboratory cages where males could not escape, and in the wild many mates leave unharmed.

Which red shape marks the underside of the abdomen of most female black widow spiders?

An hourglass is the classic mark, but some females show only two red dots or no marking at all, so a plain black spider is not proof of a harmless one.

Male black widow spiders cannot harm people mainly because which body part is too short?

Their fangs are too short to get through human skin. Only a mature female's, about a millimetre long, can deliver venom to a person.

When disturbed in its web, a black widow spider often drops to the ground and does what?

It plays dead: this timid spider lowers itself on a safety line and pretends to be lifeless rather than stand and fight.

After biting an insect and wrapping it up, how does a black widow spider actually eat its meal?

The spider drinks its liquefied body. It pours digestive enzymes onto the insect, so digestion happens outside the spider, and then it sucks up the fluid.

A female black widow spider usually waits near the centre of her web in which position?

Upside down is her normal pose: she hangs belly up and waits for an insect to blunder in, then rushes over to bite it and wrap it up.

Black widow spiderlings that run short of food soon after hatching are known to eat what?

Their own siblings are on the menu. Of the hundreds of eggs in a sac, only about thirty spiderlings usually survive the first molt, and cannibalism is one of the main reasons.

Black widow spider venom causes cramps and sweating by acting mainly on which part of the body?

The nerves are the target: the venom makes their endings release chemical messengers in a flood, which is why muscles lock into painful cramps.

Which medical term covers the muscle pain, vomiting and sweating of a black widow spider bite?

Latrodectism takes its name from the widow spiders' scientific genus. Only a substantial dose of venom brings it on, and it usually clears up within three to six days.

How did professor Allan Blair prove in 1933 that black widow spider venom harms humans?

He let one bite him and kept notes for two hours, until he could write no more. He spent two days in hospital and dropped his plan to test a second bite.

Black widow spider antivenom comes from antibodies made by which animals injected with the venom?

Horses are injected with venom over a period of time, build up antibodies and are then bled so the antibodies can be purified. The horse proteins can set off allergic reactions in patients.

Along with local sweating, which skin reaction is a telltale sign of a black widow spider bite?

Goosebumps and a patch of sweat near the bite are so typical that doctors treat them as evidence venom went in. There may be no redness or puncture marks at all.

The karakurt, Kazakhstan's Mediterranean black widow spider, is reported to kill which big animals?

Camels are among its reported victims. The species lives in steppes and grasslands, and it becomes a real problem for people where grain is still harvested by hand.

Black widow spiders belong to the comb-footed family, named for a row of bristles on which legs?

The hind pair carries a comb of strong, curved bristles, which the spider uses to fling silk over prey struggling in the web.

With very poor eyesight, black widow spiders mostly rely on what to find prey caught in their webs?

Vibrations travelling along the threads tell the spider what has landed and where. The same signals warn it of anything too large to tackle.

Black widow spiders are not aggressive, so most bites on people happen in which situation?

When pressed against skin, a trapped spider bites in self-defence, which is why gloves and boots left outdoors are classic places to get bitten. Given a way out, it flees.

Males of which Australian black widow spider relative somersault onto the female's mouthparts?

The redback male's somersault is thought to buy him a longer mating and so more fertilised eggs. An antivenom for the species' bite has been available since 1956.

New Zealand's katipō, a rare relative of the black widow spider, has a Māori name meaning what?

Night stinger joins the Māori words for 'to sting' and 'the night'. The species is in serious decline and has been fully protected by New Zealand law since 2010.

The red widow spider, a rare cousin of the black widow, lives only in which US state?

Florida is its only home: the red widow lives in the sand-pine scrub of the central and southern parts of the state, where it spins its web in palmetto bushes.

Brown widow spiders, newcomers this century, appear to be displacing black widows in which region?

Southern California is where the brown widow, which seems more hostile to its black cousin than the reverse, is taking over. Its bite is less toxic to people, so the change may be good news.

In southern Africa, black widows and their close relatives go by which common name?

Button spiders have a fearsome reputation, yet no death from a bite has been recorded in southern Africa for decades.

Which wasp, chief enemy of black widow spiders in western North America, feeds them to its young?

The blue mud dauber often takes over another wasp's abandoned mud nest, clears out the spiders stored there and restocks it with freshly caught ones for its own egg.

Which West Coast reptile often eats western black widow spiders and shrugs off their venom?

The southern alligator lizard has shown immunity to the venom, which turns one of the continent's most feared spiders into a regular snack.

Black widow spiders are thought to have reached Hawaii partly as stowaways in shipments of what?

Imported produce is a known route into the islands, where three different widow species are now established. The same pathway is thought to spread widow spiders elsewhere.

The Mediterranean black widow spider may be the real biter behind the legend of which Italian dance?

The tarantella was danced for hours as a supposed cure for a spider's bite. Legend blamed a wolf spider from Taranto, but that species is not deadly, so the local widow may have been the culprit.

What name is given to the silk a courting male black widow spider drapes over the female?

The bridal veil is a light layer of silk thrown over the female once the male has reached her. The courtship leading up to it can take anything from ten minutes to two hours.

Which American aircraft maker named its P-61 radar warplane the Black Widow after the spider?

Northrop built the P-61 as the first American warplane designed from the outset to fight after sundown, with radar built into the airframe. Its YF-23 stealth prototype was later nicknamed Black Widow II.

Astronomers borrow the black widow spider's name for which kind of star that destroys its partner?

A pulsar earns the nickname when its fierce wind of particles slowly strips away the small companion orbiting it. The first, found in 1988, spins more than 600 times a second.

What purpose does the bright red marking on a female black widow spider's underside serve?

Warning predators is its job: red on black is a classic danger signal in nature, advertising that a mouthful of this spider comes with a dose of potent venom.

Black widow spiders, which like to nest near the ground, favour which kind of place around homes?

Dark, undisturbed nooks suit them best: woodpiles, sheds, garages, basements and the space under desks or furniture, often in small holes made by other animals.

Tiny black widow spiderlings spread to new places by which airborne method, riding a strand of silk?

Ballooning spiderlings climb a fence post or plant, raise their abdomens and let out a thread until an updraft lifts them. Some land a few feet away; others have been caught 200 miles offshore.

What are the glue-tipped trap threads that run from a black widow spider's web to the ground called?

Gumfoot lines snap free when an insect blunders into the glue at their base, and the tension in the web then hoists the victim up towards the waiting spider.

Male black widow spiders read chemicals in a female's web to learn what about her before courting?

How well fed she is matters to a suitor: males prefer females that have eaten recently, and they can sense it from chemicals left in the threads.

Which ability lets a female black widow spider go on laying fertile eggs long after mating?

Storing sperm gives her a lifetime supply, enough to fertilise every egg she will ever lay. One summer can bring four to nine sacs, each packed with eggs.

Which French insect writer told of the feared Mediterranean black widow spider's reputation in Corsica?

Jean-Henri Fabre admired the spider's black velvet coat speckled with red. He noted that Corsican country people called its bite sometimes fatal, and that doctors did not always dare to disagree.

New Zealand's katipō, a declining relative of the black widow spider, lives mainly in which habitat?

Coastal dunes are its stronghold: it spins its web among dune plants and under driftwood near the shore, and the loss of that habitat is the main cause of its decline.

The Mediterranean black widow spider's Latin species name describes which feature of its back?

Thirteen spots, usually red, dot the upper side of its abdomen, and the Latin name tredecimguttatus simply counts them.