Daddy long legs are eaten by birds, spiders, scorpions, frogs, ants, bats, and small mammals, among other predators. The catch is that “daddy long legs” refers to at least three completely different creatures depending on where you live, and each one faces a different set of threats. Understanding which animal you are actually asking about changes the answer considerably.
Three Different Animals, One Nickname
Before getting into who eats what, it helps to sort out the name confusion. In most of the United States, “daddy long legs” means harvestmen, the spider-like arachnids with a single round body and impossibly thin legs that you find under rocks, in leaf litter, and sometimes clustered on the side of a building. Harvestmen belong to the order Opiliones. They are not spiders, though they are arachnids. They have no venom glands and no silk-producing spinnerets.
In the United Kingdom and Australia, “daddy long legs” commonly refers to crane flies, those fragile, gangly insects that look like oversized mosquitoes and bump into your porch light on warm evenings. Crane flies are true flies in the family Tipulidae and are completely harmless.
A third contender is the cellar spider (family Pholcidae), the wispy, long-legged spider that builds messy webs in the corners of basements and garages. Cellar spiders are actual spiders, complete with venom, silk, and fangs, though they pose zero threat to humans. All three creatures share the nickname, but they occupy different branches of the animal kingdom and face different predators. This article covers the predators and defenses of all three.
What Eats Harvestmen
Harvestmen are slow, soft-bodied, and lack venom, which makes them an easy meal for a wide variety of predators. Research on harvestmen in New Zealand confirmed that passerine birds are the most frequently documented predators. Dunnocks, starlings, and rooks, all introduced to New Zealand from Europe, feed on harvestmen there just as they do on their native continent.1BioOne Complete. Diet, predators, and defensive behaviors of New Zealand harvestmen (Opiliones: Neopilionidae) Native bird species eat them too. If you have ever watched a robin or a blackbird poking through leaf litter, there is a good chance harvestmen are on the menu.
Arthropod predators are just as significant, especially in tropical regions. Field observations in Costa Rica documented a lineup of invertebrate predators picking off harvestmen: two species of wandering spiders in the genus Cupiennius, a scorpion, a sun spider (solifuge), a praying mantis, and ants.2Caribbean Journal of Science. Defensive Responses of Neotropical Harvestmen (Arachnida, Opiliones) to Generalist Invertebrate Predators Ants in particular are a persistent threat. Because ants recruit nestmates to food sources and attack in numbers, a single harvestman caught by a scouting ant can quickly face an overwhelming swarm.
Among vertebrates, frogs and small mammals round out the predator list. Laboratory experiments testing harvestmen defenses found that at least one frog species and one opossum species readily attempted to eat harvestmen.3PubMed. Chemical defense in harvestmen (arachnida, opiliones): do benzoquinone secretions deter invertebrate and vertebrate predators? Shrews, lizards, and toads are also common predators in temperate habitats. In short, harvestmen sit fairly low on the food chain. Anything that eats small invertebrates probably eats harvestmen.
What Eats Crane Flies
Crane flies face predators at every stage of their life, from larva to adult. The larvae, often called leatherjackets, live in soil or wet organic matter and are consumed by ground beetles, birds foraging on lawns, and moles tunneling underground. Adult crane flies, once they emerge and take to the air, are clumsy fliers with no defensive capabilities whatsoever, making them prime targets.
Bats are among the most significant predators of adult crane flies. A study of two bat species in Sweden found that crane flies, along with moths, beetles, and caddisflies, made up a large portion of what these bats consumed. By volume, these relatively large nocturnal flying insects represented about half of the northern bat’s diet and close to 60 percent of the long-eared bat’s diet.4Ecography. Food habits of northern (Eptesicus nilssoni) and brown long-eared (Plecotus auritus) bats in Sweden Noctule bats, another European species, also eat large numbers of small flies alongside their preferred beetle prey.5Journal of Zoology. Flight performance, echolocation and foraging behaviour in noctule bats Nyctalus noctula
Birds that feed in the Arctic depend on crane flies in a surprisingly specific way. Bar-tailed godwit chicks rely on adult crane flies as their main food source during the brief Arctic summer. The timing of crane fly emergence on the tundra is tied to snowmelt, and shifts in when the flies appear can affect whether the chicks get enough to eat.6Nature Communications. Fuelling conditions at staging sites can mitigate Arctic warming effects in a migratory bird Swallows, swifts, and house martins snatch crane flies in flight during warmer months. Spiders catch them in webs. Even domestic cats and dogs will chase them indoors. The adult crane fly’s strategy, if you can call it that, seems to be reproducing quickly and relying on sheer numbers rather than any individual survival tactic.
Predators of Cellar Spiders
Cellar spiders live in a somewhat protected niche. By building their webs in sheltered indoor spaces, they avoid many of the predators that hunt in the open. Still, they are not immune. Other spiders are their main enemies, especially web-invading species that specialize in raiding other spiders’ webs. Jumping spiders are quick enough to catch cellar spiders despite the latter’s habit of vibrating rapidly in their webs. Parasitic wasps in the family Ichneumonidae target cellar spiders as well, laying eggs on or near the spider so that the wasp larvae can feed on the host.
Outdoors, cellar spiders face the same suite of insectivorous predators as other small spiders: birds, lizards, and larger spiders. Their thin, almost translucent bodies and tendency to hang motionless in dark corners likely help them avoid notice, but when a predator does find them, cellar spiders rely on a distinctive escape behavior rather than fighting back.
How Harvestmen Defend Themselves
Given how many things want to eat them, harvestmen have evolved a surprisingly rich toolkit of anti-predator defenses. The most dramatic is chemical warfare. Many harvestmen species have scent glands near the front of their body that release defensive secretions when they are threatened. In one well-studied South American species, these glands produce compounds called benzoquinones. Lab experiments showed that these secretions repelled seven different ant species, two species of large wandering spiders, and a frog. The chemical acted as a kind of shield, keeping predatory ants at bay for at least ten minutes, which is long enough for the harvestman to escape before the ants can recruit reinforcements.3PubMed. Chemical defense in harvestmen (arachnida, opiliones): do benzoquinone secretions deter invertebrate and vertebrate predators?
The defense is not foolproof. In the same experiments, the benzoquinone secretion had no deterrent effect on an opossum, which simply ate the harvestman regardless.3PubMed. Chemical defense in harvestmen (arachnida, opiliones): do benzoquinone secretions deter invertebrate and vertebrate predators? This fits a broader pattern: chemical defenses tend to work well against smaller predators like ants and spiders, which come into close contact with the secretion, but are less effective against larger vertebrates that can overpower the harvestman before the chemicals matter.
When the chemistry fails, harvestmen fall back on physical escape tactics. Leg autotomy, the deliberate shedding of a leg to escape a predator’s grip, is common across many species. A predator grabs a leg, the leg breaks off at a pre-formed weak point, and the harvestman scrambles away on its remaining legs. The lost leg cannot regenerate, so there is a real cost, but surviving with seven legs beats not surviving at all. Researchers in New Zealand observed that harvestmen typically tried to flee first and resorted to dropping a leg only when escape was blocked.1BioOne Complete. Diet, predators, and defensive behaviors of New Zealand harvestmen (Opiliones: Neopilionidae)
Playing dead, known as thanatosis, is the last resort. After a failed escape attempt, some harvestmen simply drop to the ground with all their legs pointing straight up and remain motionless. This behavior was documented across all species of a New Zealand harvestman family and usually appeared only after the animal had tried and failed to run away.1BioOne Complete. Diet, predators, and defensive behaviors of New Zealand harvestmen (Opiliones: Neopilionidae) Playing dead can work against predators that rely on movement to identify prey, though it is presumably useless against anything hunting by smell.
The Cellar Spider’s Whirling Trick
Cellar spiders have their own signature escape move: whirling. When a predator touches the spider or its web, or even when a puff of air disturbs it, the cellar spider swings its body rapidly in a circle while keeping its legs anchored to the silk. The motion is fast enough to make the spider a blur, which can confuse a predator trying to land a precise strike. Experiments showed that both physical contact and air movement triggered whirling, but there was no evidence that chemical cues from predators played a role.7Journal of Zoology. Anti-predator defences of Pholcus phalangioides (Araneae, Pholcidae), a web-building and web-invading spider
Interestingly, the behavior varies with age and context. Small juveniles were more likely to simply drop out of the web than to whirl when confronted by a predator, possibly because their smaller bodies generate less visual confusion when spinning. Adult females and larger juveniles whirled more reliably. Cellar spiders were also less inclined to whirl when they were in someone else’s web rather than their own, which makes sense: whirling depends on having a stable silk platform, and an unfamiliar web may not support the maneuver as well.7Journal of Zoology. Anti-predator defences of Pholcus phalangioides (Araneae, Pholcidae), a web-building and web-invading spider When invading another spider’s web, however, the whirling could deter the resident spider from attacking, giving the cellar spider an edge in these confrontations.
The Venom Myth
No discussion of daddy long legs predators is complete without addressing the persistent myth that daddy long legs are “the most venomous spider in the world, but their fangs are too small to bite you.” This claim is wrong on multiple counts. Harvestmen are not spiders and have no venom at all. Crane flies are insects with no venom either. Cellar spiders do have venom, which they use to subdue small prey, but there is no evidence that their venom is unusually potent to humans, and their fangs can in fact pierce human skin, although a bite is extremely rare and causes nothing more than a brief, mild sting.
The myth may persist partly because it makes these fragile, harmless animals seem more interesting. But their real defense strategies, spraying chemical repellents, shedding limbs, spinning into a blur, are genuinely fascinating without needing fictional superpowers.
How Artificial Light Changes Nighttime Predation
One factor affecting daddy long legs and their predators that most people do not think about is artificial light. Streetlamps, porch lights, and other outdoor lighting famously attract flying insects, including crane flies. But the effect on predation is more complex than simply drawing prey to a convenient spot for predators. A field experiment studying predation on ground-dwelling insects near lampposts found that predation rates were significantly lower after dusk than before it, and that the distance from a light source mattered. Closer to a lamppost, predation rates after dark did not drop as steeply as they did farther away, suggesting that the light altered how predators and prey interacted at night.8PubMed Central. Artificial light at night may decrease predation risk for terrestrial insects
For harvestmen, which are mostly nocturnal and forage on the ground after dark, artificial light could shift the balance in either direction. Light may make them more visible to birds that would otherwise be roosting, or it may suppress the activity of night-hunting predators that prefer true darkness. Crane flies drawn to lights are easy pickings for bats that have learned to hunt near illuminated areas, and cellar spiders indoors benefit from the insects that wander into their webs from lit porches and windows. The interplay between light pollution and predation is an active area of research, and the full picture for each “daddy long legs” group is still coming together.
Why Harvestmen Clump Together
If you have ever found a writhing ball of dozens or even hundreds of harvestmen huddled together on a tree trunk or under an overhang, you have witnessed one of their more striking behaviors. These aggregations, sometimes called “clusters” or “huddles,” likely serve multiple functions, but predator deterrence is thought to be a major one. A single harvestman is an easy target. A mass of bobbing, intertwined legs can confuse a visual predator, and a concentrated cloud of defensive chemical secretions from many individuals at once is more noxious than what one harvestman alone can produce.
The aggregations may also help with moisture retention and thermoregulation, since harvestmen are prone to drying out. But the predation angle is supported by the fact that harvestmen on the edges of a cluster, the ones most exposed to predators, tend to bob their bodies up and down more vigorously when disturbed, which may serve as a visual warning. The clusters are seasonal and more common in late summer and fall, coinciding with the period when harvestmen are most abundant and predation pressure from birds and other insectivores is high.
What Daddy Long Legs Eat Themselves
It is worth flipping the question around, because daddy long legs are not purely victims. Harvestmen are omnivorous scavengers. They eat dead insects, plant matter, fungi, bird droppings, and occasionally small live invertebrates like aphids and mites. They are not built for active hunting the way spiders are, lacking both venom and silk, but they will scavenge almost anything organic they encounter. This makes them useful decomposers in garden and forest ecosystems.
Cellar spiders, on the other hand, are active predators. They catch small insects in their webs and are known to invade the webs of other spider species, including much larger ones, to steal prey or even kill and eat the resident spider. Some homeowners leave cellar spiders alone in their basements for exactly this reason: they help control populations of other spiders, including species people find more alarming.
Crane flies, as adults, barely eat at all. Most adult crane flies have only vestigial mouthparts and survive just long enough to mate and lay eggs. The larval stage, when they live in soil and feed on decaying plant material or grass roots, is where crane flies do most of their eating. Leatherjackets can damage lawns when populations are large, which is one reason gardeners sometimes consider them pests despite the adult fly being completely harmless.