How Long Does a Daddy Long Legs Live?

It depends on which creature you mean, because “daddy long legs” refers to three completely different animals depending on where you live. Harvestmen, the eight-legged non-spider arachnids, typically live about one year. Cellar spiders, the wispy web-spinners found in basements, can survive two to three years. And crane flies, the fragile flying insects sometimes called daddy long legs in the UK, live only a few days to a couple of weeks as adults. The answer to the lifespan question starts with knowing which creature you’re actually asking about.

Three Animals, One Nickname

Few common names in the animal kingdom cause as much confusion as “daddy long legs.” In the United States, the name most often refers to harvestmen, members of the arachnid order Opiliones. They look vaguely spider-like but carry their body as a single compact oval rather than two distinct segments, and they don’t produce silk or venom. In that same country, some people also use the name for cellar spiders in the family Pholcidae, the delicate, almost translucent spiders that build messy webs in garages and corners. In the UK and parts of Australia, “daddy long legs” typically means crane flies, order Diptera, which are true flying insects with only two wings and no ability to bite or sting.

These three animals are not closely related. Harvestmen are arachnids but not spiders. Cellar spiders are genuine spiders. Crane flies are insects. Their lifespans, habitats, and biology are all different, so any discussion of how long a “daddy long legs” lives has to separate them.

Harvestmen and Their One-Year Clock

Most harvestmen species follow an annual life cycle. An egg laid in late summer or autumn hatches into a nymph that grows through a series of molts, reaches adulthood the following spring or summer, mates, and dies by autumn. The entire arc, from egg to death, takes roughly a year in temperate climates. A few species in cooler environments stretch this out to two years or occasionally longer, using dormant overwintering stages to pause development during months when food is scarce and temperatures drop.

That seasonal rhythm means the harvestmen you see wandering your garden or garage in late summer are likely near the end of their lives. They’ve reached sexual maturity, are searching for mates, and will not survive the coming winter. The eggs they leave behind carry the species through to the next year. In tropical regions, where seasons are less pronounced, some harvestmen species can be found at various life stages year-round, but even these generally don’t exceed a couple of years.

Harvestmen are also unusual among arachnids in that they are omnivores. They eat small insects, plant material, fungi, and decaying organic matter. This dietary flexibility means they can find food in a wider range of conditions, which helps them survive through lean months. Still, their small size, soft bodies, and limited defenses make them vulnerable to predators, and many individuals don’t make it through their full year.

Cellar Spiders Can Outlast Most House Spiders

Cellar spiders are the longest-lived of the three “daddy long legs” candidates. In the relatively stable environment of a heated home, with steady temperatures and a supply of small insects, a cellar spider can live two to three years. That’s a solid lifespan for a spider of this size. Many common house spiders live less than a year.

Part of what helps cellar spiders survive is that they rarely leave their webs. They build irregular, tangled webs in sheltered spots, hang upside down, and wait. When prey touches the web, the spider rapidly vibrates its body and the silk, which can entangle the prey further. When threatened by a larger predator, some cellar spiders vibrate so quickly they become a blur, making them harder to target. This low-energy, stay-in-place strategy means they burn fewer calories and face fewer risks than actively hunting spiders.

Cellar spiders also eat other spiders, including species much larger than themselves. Their long legs let them throw silk at prey from a safe distance, immobilizing it before moving in. This ability to take down competitors and potential predators in their own territory contributes to their relatively long tenure in a given corner of your home.

Crane Flies Have the Shortest Adult Lives

If your “daddy long legs” is a crane fly, the adult you’re watching probably has less than two weeks to live. Most crane fly species spend the majority of their lives as larvae, living in soil, leaf litter, or shallow water for months. The larval stage can last anywhere from a few months to over a year depending on the species and conditions. But once a crane fly emerges as a winged adult, its remaining time is brief. Many species don’t eat at all as adults because their mouthparts are vestigial or poorly developed. Their sole purpose in the adult stage is to find a mate and reproduce.

This pattern, a long developmental stage followed by a very short adult life, is common among insects. The adult crane fly’s gangly appearance and clumsy flight give the impression of fragility, and that impression is accurate. They are easy prey for birds, bats, and spiders, and they have few defenses beyond shedding a leg when grabbed.

One remarkable exception involves snow flies, a cold-adapted group of crane flies that are active in winter. Research on North American snow flies found that these insects can self-amputate their legs when ice begins forming in a limb, detaching the frozen leg before the ice wave spreads to the body. Over half of the snow flies studied lost at least one leg this way during cold exposure. Flies that amputated a frozen limb survived an average of 77 additional seconds before their body froze, and they tolerated significantly colder temperatures than flies that failed to shed the leg in time.¹ It’s a small margin, but in the wild those extra seconds at lower temperatures could mean the difference between surviving a brief cold snap and dying.

How Harvestmen Stay Alive Long Enough to Reproduce

For an animal with no venom, no silk, and a soft body, harvestmen face a hostile world. They’ve evolved several strategies to improve their odds of surviving long enough to pass on their genes.

The most dramatic is autotomy: voluntarily dropping a leg when a predator grabs it. Unlike some lizards that can regrow a lost tail, harvestmen never regenerate lost legs. The sacrifice is permanent. But it works as an escape mechanism, and harvestmen are surprisingly resilient afterward. Research has shown that harvestmen that lost up to three legs recovered their initial running speed within just two days, making them the fastest-recovering autotomizing animal studied. They compensated by adjusting their stride, shifting their posture, and even recruiting their elongated sensory legs for walking.²

That quick recovery in sprint speed comes with costs, though. Separate experiments found that while losing a single leg didn’t measurably change how much energy a harvestman burned while moving, losing three legs increased oxygen consumption during locomotion. Endurance also dropped gradually with each leg lost, meaning a harvestman missing several legs could sprint away from an immediate threat but might not sustain movement over longer distances.³ In the wild, this tradeoff probably matters. Escaping one predator is only useful if you can still forage and find mates afterward.

Harvestmen also deploy chemical weapons. Many species have specialized scent glands that release defensive secretions when threatened. In one well-studied species, the secretions contain benzoquinones, compounds that effectively repelled ants, large wandering spiders, and frogs. The chemical created a kind of protective shield around the harvestman, keeping aggressive ants at bay for at least ten minutes and giving the harvestman time to escape before more ants could be recruited to the area.⁴ The defense wasn’t foolproof, though. An opossum in the same study was unfazed by the secretion, which underlines the reality that no single defense works against everything.

Cellar Spiders and the Risks of Motherhood

Cellar spiders have an unusual approach to egg care that illustrates some of the survival pressures they face. Instead of attaching their egg sac to the web and leaving it, female cellar spiders carry the egg sac in their jaws, holding it with their chelicerae as they hang from the web. This means the mother can’t eat while carrying eggs, and she’s limited in her ability to defend herself.

Research on the cellar spider Holocnemus pluchei revealed that this dedication pays off. Egg sacs that were continuously guarded by the mother had a perfect hatching rate. Without maternal protection, eggs were vulnerable to fungal infections in humid conditions and to cannibalism by other spiders in the area. Interestingly, females were more willing to temporarily set aside their eggs to mate when the eggs were already well-developed, at around 14 to 18 days after being laid, compared to newly laid eggs at 3 to 6 days old.⁵ The later-stage eggs were more resistant to environmental hazards on their own, so the mother’s absence posed less risk.

This investment in offspring protection may be part of why cellar spiders can maintain stable populations in homes. Each female that successfully guards a clutch through to hatching produces a batch of spiderlings that have a decent chance of surviving, rather than scattering hundreds of eggs and hoping a few make it. The tradeoff is that the mother goes weeks without food and exposes herself to risk during the carrying period.

What Actually Kills Them

For all three types of “daddy long legs,” the most common causes of death vary by habitat. Harvestmen in the wild are eaten by birds, frogs, spiders, beetles, and small mammals. Their chemical and autotomy defenses help, but a significant portion of each generation is consumed before reaching reproductive age. Cold winters kill many individuals directly, and those that survive do so as eggs or dormant juveniles rather than as active adults.

Cellar spiders in homes face fewer predators but are not immune. Other spiders, particularly more aggressive species, will kill them. Homeowners wielding brooms are a major source of mortality. In unheated buildings, winter temperatures can kill cellar spiders that have adapted to warmer indoor conditions. Starvation is another risk: a cellar spider in a corner with no insect traffic will eventually run out of prey.

Crane flies are eaten by practically everything. Birds, bats, frogs, fish, dragonflies, and spiders all take them readily. Their thin bodies and slow, erratic flight make them easy targets. Because the adult stage is so brief and vulnerable, crane fly populations depend on the larval stage being productive enough to compensate for massive adult mortality. Larvae in soil and water face their own predators, including beetles and parasitic wasps, but they’re better protected by their environment than the exposed adults.

The Venomous Daddy Long Legs Myth

No discussion of daddy long legs would be complete without addressing the persistent myth that they possess incredibly potent venom but can’t deliver it because their fangs are too small. This claim, which has circulated for decades, is wrong on every level for harvestmen and misleading for cellar spiders.

Harvestmen have no venom glands at all. They are not venomous, period. They don’t have fangs in the spider sense; their chelicerae are used for grasping food, not injecting anything. The myth simply doesn’t apply to them.

Cellar spiders do have venom and fangs and can theoretically bite a person, though they rarely do and the bite is not medically significant. The venom has never been shown to be unusually potent. Their fangs are small, but claims that they physically cannot pierce human skin have been tested and debunked. They can, in rare cases, break the skin, but the resulting bite is comparable to a mild pinprick with negligible symptoms.

Crane flies have no venom and no biting mouthparts as adults. They are completely harmless to humans.

The myth persists partly because people conflate the three creatures. Someone hears “daddy long legs are the most venomous” and applies it indiscriminately to whichever leggy creature they associate with the name. None of the three is dangerous to people.

Why Harvestmen Gather in Clusters

If you’ve ever found a dense ball of harvestmen clinging together on a wall or under an overhang, you’ve witnessed one of their more striking behaviors. Harvestmen frequently aggregate in groups that can number in the dozens or even hundreds. These clusters seem to serve several purposes. They may reduce water loss, since a mass of bodies has less surface area exposed per individual than each animal would have on its own. The clusters could also amplify their chemical defenses, concentrating the benzoquinone secretions that deter predators. A predator encountering a writhing mass of long-legged arachnids releasing foul-smelling chemicals is likely to reconsider the meal.

Aggregation typically happens in sheltered, humid spots like cave entrances, rock overhangs, and shaded building exteriors. The clusters are not social in the way ant colonies are. There’s no cooperation, no division of labor, no shared offspring care. Individual harvestmen join and leave as conditions change. But the behavior is common enough and conspicuous enough that it’s often the context in which people first encounter harvestmen and start wondering what they’re looking at and how long these creatures stick around.

For harvestmen nearing the end of their annual cycle, these aggregations may also serve as mating congregations, bringing individuals together at the right time. By late summer and early autumn, when harvestmen are most visible and most likely to gather in groups, the adults have only weeks left. The legs they’ve sacrificed, the chemicals they’ve sprayed, and the winters they’ve endured as dormant juveniles have all been in service of reaching this final window to reproduce before the season turns.