The answer is either six or eight, depending on which creature you mean. The name “daddy long legs” is applied to three completely different animals across the English-speaking world: harvestmen, cellar spiders, and crane flies. Two of them are eight-legged arachnids, while the third is a six-legged insect. The confusion is so ingrained that many people go their entire lives without realizing they may be picturing a different animal than the person they’re talking to.
Three Animals, One Nickname
The root of the confusion is that “daddy long legs” is a folk name, not a scientific one, and it landed on three unrelated creatures simply because all three have notably long, spindly legs relative to their body size. The animals share almost nothing else in common. Understanding which one someone means usually comes down to geography and context.
Harvestmen (order Opiliones) are the creatures most commonly called daddy long legs in the United States, Canada, and much of the world. They are arachnids, meaning they have eight legs, but they are not spiders. Their compact, pill-shaped body looks like a single round segment because the two main body sections are fused together, giving them an appearance very different from a spider’s clearly two-part silhouette. With over 6,500 described species worldwide, harvestmen are the third-largest group of arachnids.1PubMed Central. Eggs to long-legs: embryonic staging of the harvestman Phalangium opilio (Opiliones), an emerging model arachnid You’ll typically find them outdoors, in leaf litter, gardens, and on shaded walls.
Cellar spiders (family Pholcidae) are the ones commonly called daddy long legs in the United Kingdom, Australia, and New Zealand. These are true spiders, with eight legs, two distinct body segments, and the ability to spin silk webs. They hang upside down in messy, irregular webs in basements, garages, and ceiling corners. Their legs are extraordinarily thin and long for their body size, which earned them the shared nickname.
Crane flies (families Tipulidae and Limoniidae, among others) get the “daddy long legs” label in parts of Britain and Ireland. These are insects, so they have six legs and a pair of wings. They look like oversized, gangly mosquitoes and are often seen bumbling around porch lights on summer evenings. They cannot bite or sting, and despite their mosquito-like appearance, adult crane flies either feed on nectar or don’t eat at all during their short adult lifespan.
How to Tell Them Apart
If you’ve found a daddy long legs and want to know which kind it is, the quickest clues are body shape, wings, and web.
- Wings: If it has wings, it’s a crane fly and therefore an insect with six legs. Neither harvestmen nor cellar spiders have wings.
- Web: If it’s hanging in a web, it’s almost certainly a cellar spider. Harvestmen do not produce silk and never build webs.
- Body segments: If it has a single rounded body that looks like one piece, it’s a harvestman. Cellar spiders have a visible narrow “waist” separating their front and rear body sections, just like other spiders.
- Eyes: Harvestmen have a single pair of eyes set on a small turret on top of their body. Cellar spiders, like most spiders, have multiple pairs of eyes clustered on the front of their head region.
Counting legs also works as a tiebreaker against crane flies specifically: six legs plus wings equals crane fly, eight legs and no wings means you’re looking at one of the two arachnids.
Why Harvestmen Are Not Spiders
People often assume harvestmen are a type of spider, and it’s an understandable mistake. Both belong to the class Arachnida, which also includes scorpions, ticks, and mites. But harvestmen sit in their own order, Opiliones, which is entirely separate from the spider order, Araneae. The split between these two lineages happened hundreds of millions of years ago, with fossil and molecular evidence placing harvestman diversification as far back as the late Silurian to mid-Carboniferous periods, making some fossil harvestmen among the earliest known land animals.2PubMed Central. Phylogenomic resolution of paleozoic divergences in harvestmen (Arachnida, Opiliones) via analysis of next-generation transcriptome data
The differences between harvestmen and spiders go beyond appearance. Harvestmen lack venom glands entirely. They also lack silk glands. They breathe through a different type of respiratory system than spiders use. And their fused body plan, where the abdomen and cephalothorax are broadly joined, is a fundamentally distinct body architecture. In practical terms, a harvestman is about as closely related to a spider as a scorpion is.
The Venom Myth
One of the most persistent urban legends about daddy long legs is the claim that they are the most venomous creatures on Earth but their fangs are too small to pierce human skin. This myth has circulated for decades and tends to float freely between all three animals that share the name, which makes it triply wrong.
Harvestmen have no venom at all. They lack venom glands and fangs entirely, so the myth doesn’t even get off the ground for the most commonly identified daddy long legs. They catch prey by grabbing it with their mouthparts or legs, not by envenomating it.
Cellar spiders do have venom, as all true spiders do (with a couple of rare exceptions). But research on pholcid spider venom has shown that it is not particularly potent. A study on the venom of the pholcid species Physocyclus mexicanus found that documented bites on humans produce only a mild sting with no lasting effects, and the researchers concluded that the effects of pholcid bites on humans and other mammals are inconsequential.3PubMed Central. Not so Dangerous After All? Venom Composition and Potency of the Pholcid (Daddy Long-Leg) Spider Physocyclus mexicanus Their fangs are also perfectly capable of biting humans, just as a tiny pinprick. So neither half of the myth holds up: the venom is mild, and the fangs work fine.
Crane flies, being insects, have neither fangs nor venom. They can’t bite at all. So no matter which daddy long legs the myth is applied to, it collapses.
Those Extraordinary Legs
The legs are obviously the defining feature that connects all three animals in the public imagination, but harvestmen take leg specialization to a level the other two don’t match. One pair of their eight legs, typically the second pair, is elongated well beyond the others and modified to serve primarily as sensory organs rather than for walking.1PubMed Central. Eggs to long-legs: embryonic staging of the harvestman Phalangium opilio (Opiliones), an emerging model arachnid You can sometimes watch a harvestman walking on six legs while sweeping those extra-long second legs ahead of it like antennae, tapping the ground and objects to gather chemical and tactile information about its surroundings. In many species, these sensory legs are several times the length of the body itself.
This sensory arrangement is one reason harvestmen are so successful despite lacking the silk and venom that make spiders effective predators. They navigate their world through touch and chemical detection, finding food and avoiding threats with those constantly probing front legs. It’s a strategy that has worked for over 400 million years.
What Happens When They Lose a Leg
If you’ve ever picked up a harvestman and had a leg come off in your hand while the animal scurried away, you’ve witnessed autotomy, the deliberate shedding of a limb to escape danger. Harvestmen use this strategy heavily in the wild, and unlike crabs or some other arthropods, they cannot regrow a lost leg, not even if the loss occurs before they reach maturity.4PubMed Central. Rapid recovery of locomotor performance after leg loss in harvestmen Whatever legs they lose, they lose permanently.
That makes the trade-off genuinely costly. Research on two North American harvestman species found that losing legs affects mobility, foraging ability, and sensory perception.5Canadian Journal of Zoology. Costs associated with leg autotomy in the harvestmen Leiobunum nigripes and Leiobunum vittatum (Arachnida: Opiliones) Losing a sensory leg is particularly damaging, since the animal is essentially giving up one of its primary tools for navigating the environment. Yet the behavior persists because the alternative, being eaten by a predator, is obviously worse.
What’s remarkable is how quickly harvestmen adapt to the loss. Experimental work on Prionostemma harvestmen showed that animals that lost up to three legs, or two legs on the same side of the body, experienced an immediate drop in speed and acceleration but recovered their original locomotor performance within just two days. That is the fastest post-autotomy recovery documented in any animal that sheds limbs.4PubMed Central. Rapid recovery of locomotor performance after leg loss in harvestmen How they manage it isn’t entirely clear. The researchers tracked the animals’ three-dimensional movement patterns and found that they adjust their gait to compensate, but the speed of the recovery suggests there may be more to it than simple behavioral adjustment.
Crane flies, interestingly, also shed legs, though the context is very different. A study on snow flies, a group of wingless crane flies that are active in winter, found that these insects will self-amputate a leg when ice begins to form on it, essentially sacrificing the limb to prevent ice crystals from spreading into their vital organs. Snow flies that amputated a freezing limb survived significantly longer and tolerated lower temperatures than those that didn’t.6PubMed Central. Snow flies self-amputate freezing limbs to sustain behavior at sub-zero temperatures It’s a last-resort survival tactic, and a striking example of how the same basic strategy, sacrificing a leg to stay alive, shows up independently across very different branches of the arthropod family tree.
How Harvestmen Defend Themselves Without Venom or Silk
Without venom to subdue threats and without silk to retreat into a web, harvestmen rely on a different defensive toolkit. Besides leg autotomy, their primary chemical defense comes from specialized structures called ozopores, which are openings connected to repugnatorial glands. When harassed, harvestmen secrete noxious chemicals from these glands that are foul-tasting or irritating to predators.1PubMed Central. Eggs to long-legs: embryonic staging of the harvestman Phalangium opilio (Opiliones), an emerging model arachnid The specific chemicals vary between species, but the effect is broadly the same: a predator that grabs a harvestman gets a mouthful of something unpleasant enough to reconsider.
Some harvestmen also play dead, curling their legs underneath them and remaining motionless. Others will bob their bodies rhythmically when disturbed, a behavior thought to make them harder for a predator to target or to exaggerate their apparent size. The combination of chemical deterrence, autotomy, and behavioral tricks has clearly been effective enough over geological time, given that the lineage has thrived since well before dinosaurs existed.
Where in the World Each Name Applies
The geographic split in naming can trip up travelers and internet conversations alike. In most of the United States and Canada, if someone says “daddy long legs,” they almost always mean a harvestman. In the United Kingdom and Ireland, the same phrase more often refers to crane flies, especially in casual conversation. In Australia and New Zealand, it typically means cellar spiders. All three usages are entrenched and considered correct within their respective regions, and none of them are going away.
This matters beyond trivia because advice about daddy long legs often doesn’t specify which creature is being discussed. A pest control article about keeping daddy long legs out of your house probably means cellar spiders if it’s from an Australian source and crane flies if it’s British. An American blog assuring you that daddy long legs eat garden pests is talking about harvestmen. If you read that daddy long legs are harmless, that’s true for all three, but the reasons differ: harvestmen have no venom, cellar spider venom is too weak to matter, and crane flies can’t bite.
Scientists avoid the ambiguity by using the common names specific to each group. “Harvestmen” refers exclusively to Opiliones. “Cellar spiders” or “pholcids” refers to the spider family Pholcidae. “Crane flies” refers to several related insect families in the infraorder Tipulomorpha. If you want to be understood clearly across geographic borders, using these names instead of “daddy long legs” saves everyone some confusion.
Harvestman Social Behavior
One behavior that surprises people who think of harvestmen as solitary creatures is their tendency to aggregate in large clusters. In late summer and fall, some species gather in dense groups of dozens, hundreds, or even thousands of individuals on walls, under overhangs, or in cave entrances. These aggregations are not mating swarms. The most widely supported explanation is that clustering helps with moisture retention and temperature regulation, since harvestmen are unusually vulnerable to desiccation compared to many other arachnids. The clusters may also amplify chemical defenses, with many individuals simultaneously releasing repugnatorial secretions creating a more effective deterrent than any one animal could produce alone.
If you disturb one of these groups, the whole mass will often ripple and bob in unison, which is visually startling to humans and presumably effective against birds and other visual predators. The clusters tend to form in the same locations year after year, and the sight of a pulsating ball of long-legged arachnids on a basement wall has probably generated more than a few panicked phone calls to exterminators, despite the animals being completely harmless.
Crane Flies and the “Giant Mosquito” Problem
Crane flies have their own identification problem beyond the daddy long legs name: people frequently mistake them for enormous mosquitoes. Their slender bodies, long legs, and single pair of functional wings give them a silhouette that, at a glance, looks like a mosquito scaled up to nightmare proportions. This resemblance leads to genuine fear in people who assume they bite, and it has spawned the additional folk names “mosquito hawk” and “skeeter eater,” both based on the false belief that crane flies prey on mosquitoes.
In reality, most adult crane flies don’t feed at all. Their mouthparts are not designed for piercing skin or sucking blood. The adults exist primarily to mate and lay eggs, and many species live only a few days in their winged adult form. The larval stage, spent in soil or water, is where crane flies do most of their eating, typically feeding on decaying organic matter and roots. In large numbers, crane fly larvae can damage lawns, which is the only context in which they’re genuinely a pest.
The confusion with mosquitoes also leads to unnecessary killing. Crane flies that wander indoors are disoriented, short-lived, and incapable of harming you. Catching one in a cup and putting it back outside, or simply leaving it alone, is all the intervention needed. Their clumsy, lurching flight pattern and tendency to bounce off walls and lampshades is a product of their lightweight build and relatively poor flight control, not aggressive behavior.