A daddy long legs bite, if you’re talking about the cellar spider that lives in the corners of your house, produces nothing more than a brief, mild sting that fades quickly and leaves no lasting effects. Researchers who have documented bites on human skin describe the sensation as inconsequential, roughly comparable to a faint pinprick. But the real wrinkle here is that “daddy long legs” refers to at least three completely different creatures depending on where you live, and two of them cannot bite you at all.
Three Creatures, One Nickname
The name “daddy long legs” gets applied loosely to three unrelated animals, and the answer to what happens when one bites you depends entirely on which one you mean. In most of the United States, the name usually refers to cellar spiders, the wispy, long-legged spiders that hang in messy webs in basements and garages. These belong to the family Pholcidae, and they are genuine spiders with fangs and venom. In many parts of the world, especially the UK, Australia, and rural North America, “daddy long legs” means harvestmen, the round-bodied, stilt-legged creatures from the order Opiliones. Harvestmen are arachnids but are not spiders. They have no fangs, no venom glands, and no silk. They cannot bite. In still other regions, the name refers to crane flies, those gangly, mosquito-looking insects that bump into porch lights on summer evenings. Crane flies have no mouthparts capable of biting humans.
So right away, if you’re worried about a daddy long legs bite, the first step is figuring out which animal you actually encountered. If it was dangling from a thin, disorganized web, it was a cellar spider. If it was walking freely across a wall or the ground with no web in sight, it was probably a harvestman. If it was flying, it was a crane fly. Only the cellar spider can bite, and even that bite is medically trivial.
What a Cellar Spider Bite Actually Feels Like
Cellar spiders rarely bite people, and when they do, it is almost always because they were deliberately provoked or pressed against the skin. The fangs of adult male cellar spiders can pierce uncalloused human skin, but they are small and deliver a tiny amount of venom. The most publicly documented bites occurred during an episode of the TV show Mythbusters, where a male cellar spider (Physocyclus mexicanus) bit a person from aggression, producing a brief mild sting and nothing more.1Frontiers in Ecology and Evolution. Not so Dangerous After All? Venom Composition and Potency of the Pholcid (Daddy Long-Leg) Spider Physocyclus mexicanus – Section: Notes on P. mexicanus Behavior and Effects of Bites on Humans
There is no swelling, no redness that lasts, no tissue damage, and no systemic reaction. The sensation is less intense than a mosquito bite and considerably less than a bee sting. You would not need to treat it with anything. No cases of medically significant envenomation from a pholcid spider have been documented in the scientific literature. For most people, the bite would go unnoticed if they were not watching the spider do it.
The “Most Venomous Spider” Myth
The urban legend claims that daddy long legs are actually the most venomous spiders in the world, but their fangs are too small or too weak to penetrate human skin. This is wrong on every count. The myth has been repeated so often that it has become one of the most durable pieces of arachnid folklore, but researchers have tested both halves of the claim and found them false.
First, the fangs. Adult male cellar spiders can and do penetrate human skin, as documented in both lab settings and the Mythbusters demonstration. The fangs are small, but “too small to bite” is simply inaccurate for adult males on uncalloused skin.1Frontiers in Ecology and Evolution. Not so Dangerous After All? Venom Composition and Potency of the Pholcid (Daddy Long-Leg) Spider Physocyclus mexicanus – Section: Notes on P. mexicanus Behavior and Effects of Bites on Humans
Second, the venom. When researchers tested crude venom from P. mexicanus on crickets, the dose needed to paralyze them was comparable to that of other spider species in the same broad taxonomic group. Cellar spider venom is not unusually potent. It is ordinary spider venom that happens to be delivered in very small quantities by a spider with very little interest in biting large animals. The researchers concluded that the effects of pholcid bites on humans and other mammals are “inconsequential.”2Frontiers in Ecology and Evolution. Not so Dangerous After All? Venom Composition and Potency of the Pholcid (Daddy Long-Leg) Spider Physocyclus mexicanus – Section: Venom Potency Analysis
That said, the venom itself is biochemically interesting. Analysis of the venom proteome identified 17 new groups of peptides, many of which are related to known spider toxin families. The most abundant components are metalloprotease enzymes rather than neurotoxins, which helps explain why the venom has so little effect on mammals. The researchers view pholcid venom as a source of potentially useful new peptides for biomedical research rather than any kind of danger.3PubMed Central. Not so Dangerous After All? Venom Composition and Potency of the Pholcid (Daddy Long-Leg) Spider Physocyclus mexicanus
Harvestmen Cannot Bite You at All
If your “daddy long legs” was a harvestman rather than a cellar spider, there is nothing to worry about because harvestmen lack the equipment to bite. They have no venom glands. Their mouthparts are small, pincer-like structures designed for scavenging and eating decomposing organic matter, not for piercing skin. The “most venomous” myth gets applied to harvestmen even more often than to cellar spiders, which is especially absurd because harvestmen produce no venom whatsoever.
What harvestmen do have is a chemical defense system. When threatened, some species eject a secretion from large scent glands on their body. In at least one species, Egaenus convexus, researchers have identified the secretion as mainly composed of a type of compound called a hydroxy-γ-lactone, which is smelly and presumably unpleasant to predators.4PubMed Central. A Novel Class of Defensive Compounds in Harvestmen: Hydroxy-γ-Lactones from the Phalangiid Egaenus convexus This is purely a deterrent against things that want to eat them. It is not injected, not toxic to humans, and has nothing to do with venom. If a harvestman walks across your hand, the worst it can do is leave a faintly unpleasant smell on your skin.
Harvestmen also have a habit of detaching their own legs when grabbed, which can startle people but is a standard escape tactic. The detached leg continues twitching for a while, distracting the predator while the harvestman scurries away. None of this involves any risk to you.
When a “Spider Bite” Is Not a Spider Bite
A surprisingly common real-world problem is that people attribute skin lesions to spider bites when the actual cause is something else entirely. This matters because if you wake up with a red, swollen, or blistering mark and assume a daddy long legs did it, you might ignore the real cause, which could be a bacterial infection that needs medical attention.
The misdiagnosis of spider bites is a well-documented issue in medicine. Studies have found that bacterial infections, particularly MRSA (methicillin-resistant Staphylococcus aureus), are frequently diagnosed as spider bites. The list of conditions commonly mistaken for spider bites also includes viral and fungal infections, inflammation of blood vessels, other arthropod stings, allergic reactions, chemical burns, and even diabetic ulcers.5Oxford Academic (Journal of Medical Entomology). Misdiagnosis of Spider Bites: Bacterial Associates, Mechanical Pathogen Transfer, and Hemolytic Potential of Venom From the Hobo Spider, Tegenaria agrestis
The pattern is consistent: a patient shows up with a wound, nobody saw a spider do it, but “spider bite” becomes the working explanation because it sounds plausible and the patient may have seen a spider in their home recently. In many documented cases, what was initially reported as a spider bite with necrotic tissue turned out to be a bacterial infection that required antibiotics. This is especially concerning with MRSA, which can worsen quickly without proper treatment.
The practical takeaway is straightforward. If you have an unexplained skin wound that is getting worse, expanding, swelling, or producing pus, do not dismiss it as a spider bite, especially if you did not actually see a spider bite you. A cellar spider bite, if it even left a mark, would produce no swelling, no tissue damage, and no wound that worsens over time. Anything that escalates beyond a momentary sting was not a daddy long legs and warrants a visit to a doctor.
Why Cellar Spiders Are in Your House
Cellar spiders are among the most common household arthropods worldwide. They thrive in the still, relatively humid conditions found in basements, crawl spaces, closets, and the upper corners of rooms. Unlike many spiders that wander or build geometric webs, cellar spiders create loose, irregular webs and stay in them for extended periods, hanging upside down and waiting for small insects to stumble in.
A study of arthropod communities in homes found that cellar spiders (Pholcidae) were one of 11 core arthropod families consistently found across surveyed houses. The only household variable significantly associated with their occurrence was clutter: homes with more clutter tended to have cellar spiders in a slightly higher proportion of rooms.6Scientific Reports. The Habitats Humans Provide: Factors affecting the diversity and composition of arthropods in houses This makes intuitive sense. Undisturbed corners, boxes, and storage areas provide the dark, sheltered spots these spiders prefer.
If you want fewer cellar spiders around, reducing clutter and vacuuming corners and ceiling edges regularly will remove both the spiders and their webs. There is no pest-control urgency here, though. Cellar spiders eat small insects including mosquitoes, gnats, and occasionally other spiders. Many entomologists consider them mildly beneficial housemates. They are not aggressive, not drawn to beds or clothing, and not interested in biting people. Their instinct when disturbed is to vibrate rapidly in their web, blurring their outline to make themselves harder for predators to grab.
Should You Kill Them or Leave Them Alone
This is a personal preference question rather than a safety one. There is no medical, ecological, or structural reason you need to eliminate cellar spiders from your home. They are not dangerous, they do not damage property, and they do not reproduce in large enough numbers to constitute an infestation in most homes. If you find their webs unsightly, sweeping or vacuuming them periodically keeps their numbers in check without pesticides.
Some people intentionally leave cellar spiders in place because they reduce populations of less welcome insects. Cellar spiders are known to capture and eat other spiders as well, including species that people are more wary of. Whether this pest-control benefit outweighs the aesthetic cost of having cobweb-like structures in your corners is your call.
For anyone with a genuine spider phobia, it is worth knowing that cellar spiders are among the most docile and non-threatening spiders you can encounter indoors. They cannot jump, they move slowly, and they avoid contact with humans. If you relocate one outside, it will likely die within a few days, since cellar spiders are adapted to indoor environments and do not survive well in outdoor temperature swings. Leaving them in an out-of-the-way spot they have already chosen is the path of least disruption for everyone involved.
How to Tell if a Spider Actually Bit You
Given how often skin conditions are wrongly attributed to spiders, it helps to know what a legitimate spider bite looks like compared to other causes. A genuine spider bite almost always involves the person seeing or feeling the spider at the time. Spiders do not seek out sleeping humans to bite, and they rarely bite unless physically pressed against the skin or cornered.
If you did see a cellar spider bite you, expect a tiny red dot that fades within an hour, with a mild stinging sensation that lasts only seconds. No treatment is needed. If the mark is larger than a small pimple, is growing, is warm to the touch, or is painful beyond a mild sting, a spider almost certainly did not cause it. As medical research has made clear, the conditions most commonly misdiagnosed as spider bites include MRSA and other bacterial infections, which can produce serious tissue damage if left untreated.5Oxford Academic (Journal of Medical Entomology). Misdiagnosis of Spider Bites: Bacterial Associates, Mechanical Pathogen Transfer, and Hemolytic Potential of Venom From the Hobo Spider, Tegenaria agrestis
The rare spiders whose bites do cause medically significant reactions in North America are the brown recluse and the black widow. Both look nothing like a daddy long legs. Brown recluses are small, brown, violin-marked spiders that live in undisturbed areas in the southern and central United States. Black widows are glossy black with a red hourglass marking. If you suspect a bite from either of these species, seek medical care. But if the spider in question was a thin, delicate creature dangling upside down in a web, you can safely assume it was a cellar spider and that the bite, if it happened, will be gone before you finish thinking about it.