What Do Daddy Long Legs Eat and How Do They Hunt?

The answer depends on which creature you mean, because “daddy long legs” is one of the most confusing common names in the animal kingdom. It refers to at least three completely different creatures depending on where you live: harvestmen (the leggy arachnids often found under logs), cellar spiders (the wispy web-builders in your basement), and crane flies (the gangly flying insects that bump into your porch light). Each eats differently, hunts differently, and belongs to a different branch of the animal family tree. Most people asking this question are thinking of harvestmen or cellar spiders, and the two could hardly be more different in how they get a meal.

Three Creatures, One Nickname

The confusion matters because what you call a daddy long legs shapes the entire answer to “what does it eat?” In the United States, “daddy long legs” most often means harvestmen, order Opiliones. In the UK and Australia, the same phrase usually means crane flies, order Diptera, which are not even arachnids. And in many households worldwide, people use the name for cellar spiders, family Pholcidae, which are true spiders with fangs and venom glands. Harvestmen have no venom and no silk. Cellar spiders have both. Crane flies, as adults, barely eat at all. So let’s take each one in turn, starting with the creature most people picture when they hear the name.

What Harvestmen Eat

Harvestmen are omnivores with remarkably broad tastes. They eat small invertebrates like aphids, mites, springtails, beetle larvae, and snails. They scavenge dead insects and other animal remains. And they eat a surprising amount of plant-based food. A review of feeding records found 96 documented cases of harvestmen consuming vegetable matter: 41 involved fungal material, 39 involved fruit pulp, and 16 involved seeds or seed appendages.¹ The fungi they favor tend to be small forest mushrooms, with species in the families Marasmiaceae and Mycenaceae making up about two-thirds of fungus-feeding records.

In the Northern Hemisphere, harvestmen in the genus Leiobunum have been repeatedly observed eating blackberry and raspberry fruits. In tropical forests of Central and South America, harvestmen from different families feed on the pulp of fallen fruits on the forest floor.¹ This breadth of diet is unusual among arachnids. Most spiders, scorpions, and their relatives are strict predators. Harvestmen are more like tiny raccoons: they’ll eat almost anything they stumble across.

Bird droppings, decaying organic matter, and even other harvestmen round out the menu. If a harvestman finds something soft or moist enough to bite into, it will probably try eating it. This scavenging lifestyle means harvestmen play a quiet but real role in nutrient cycling in forest ecosystems, breaking down fallen fruit, recycling dead insects, and grazing on fungi that are themselves decomposing plant material.

How Harvestmen Eat Without Venom

Here is where harvestmen diverge sharply from spiders. Spiders are liquid feeders: they inject venom to paralyze prey, then either flood the body with digestive enzymes and slurp up the resulting soup, or physically mash the prey and filter out the solids. Harvestmen do something far simpler. They are solid food feeders, meaning they bite off small chunks and swallow them. Their mouthparts, called chelicerae, work like tiny pincers that tear and chew food rather than inject it with anything.²

This solid-feeding ability is precisely what lets harvestmen eat mushrooms, fruit pulp, and seeds. A spider, limited to liquid feeding, cannot do much with a chunk of berry or a mushroom cap. A harvestman simply bites into it. This mechanical difference in feeding helps explain why harvestmen have evolved such an omnivorous diet while their spider cousins remain almost exclusively predatory.

When harvestmen do hunt live prey, the approach is straightforward: they grab it with their pedipalps (the pair of appendage-like limbs near their mouth) and chelicerae, pin it down, and start eating. There is no web, no venom, and no elaborate ambush strategy. For small, soft-bodied prey like aphids or mites, brute force with tiny pincers is plenty. For larger prey, some species have evolved more impressive equipment.

Harvestmen That Hunt Frogs

One of the more startling discoveries in recent arachnology is that some large harvestmen actively hunt and kill frogs. Not tadpoles or frog eggs, but postmetamorphic frogs, the ones with four legs that can jump. Multiple predation events involving several harvestman species and different frog species have been documented in the Neotropics, suggesting these interactions happen more often than researchers previously assumed.³

How does a venomless arachnid take down a vertebrate several times its own size? The answer lies in body armor and weaponry. Many harvestmen in the suborder Laniatores have a heavily hardened dorsal shield, robust chelicerae, and pedipalps lined with spines that help restrain struggling prey.³ Imagine a pair of spiny grasping arms and a set of powerful pincers, all mounted on a body encased in a tough exoskeletal plate. The harvestman grabs the frog, holds on through its thrashing, and begins feeding while the prey is still alive. It is not elegant, but it works. These tropical harvestmen can have leg spans exceeding a hand’s width, which changes your mental image of the harmless little leggy thing under your porch step.

Vertebrate prey is not typical. The vast majority of harvestmen meals are small invertebrates and plant matter. But the frog-hunting observations upend the old assumption that harvestmen are passive scavengers incapable of capturing anything lively. Researchers now think the full predatory range of harvestmen, especially large tropical species, has been substantially underestimated simply because nobody was looking closely enough.

What Cellar Spiders Eat and How They Hunt

Cellar spiders (Pholcidae), the other major creature called “daddy long legs,” are true spiders and hunt in an entirely different way. They spin loose, irregular webs in sheltered spots like basements, garages, and the corners of rooms. When an insect blunders into the web, the cellar spider rushes over and throws silk at the prey from a distance, wrapping it rapidly with its long legs while staying as far from the prey’s jaws as possible. Once the prey is immobilized in silk, the spider bites it, injecting venom to finish the job.

Cellar spiders eat mosquitoes, flies, gnats, beetles, and other household insects that wander into their webs. They are also known to invade other spiders’ webs and kill the residents, a behavior called araneophagy. Some cellar spiders have been observed entering the webs of much larger spiders, vibrating the silk to mimic trapped prey, and then attacking when the host spider approaches. This aggressiveness makes them surprisingly effective pest controllers in homes. If you have cellar spiders, you probably have fewer other spiders and fewer flying insects in those spaces.

Their venom, while effective on insects, is not dangerous to people. A study of the pholcid spider Physocyclus mexicanus found that its venom could paralyze crickets at a dose of about 3.9 micrograms per gram of body weight, which is comparable to the venom potency of other small spider groups. But bites on humans typically produce nothing more than a mild sting with no lasting effects.⁴ This directly contradicts the popular myth that daddy long legs have “the most dangerous venom in the world but fangs too small to bite you.” Cellar spiders can bite, their fangs do penetrate skin, and the result is trivial.

The Venom Myth, Untangled

That myth deserves a closer look because it gets applied to both harvestmen and cellar spiders, and it is wrong for different reasons in each case. Harvestmen have no venom glands at all. They have no fangs in the spider sense. They cannot inject anything into anything. The myth is physically impossible for them. Cellar spiders do have venom and can bite, but as the research on Physocyclus mexicanus showed, the venom’s effects on mammals are inconsequential.⁴ There is no hidden super-venom being held back by inadequate fangs. The myth likely persists because cellar spiders sometimes kill larger, more visibly fearsome spiders, and people assume that must require extraordinarily potent venom. In reality, the cellar spider’s advantage is its silk-throwing technique and its willingness to engage, not any special chemical weapon.

The confusion is compounded by the fact that people rarely distinguish between harvestmen and cellar spiders. Both are spindly, both live in dark corners, and both carry the daddy long legs label. When someone tells you “daddy long legs have deadly venom,” they may not even know which animal they are talking about, and neither version of the claim holds up.

How Harvestmen Defend Themselves

Since harvestmen have no venom and no silk, you might wonder how they avoid being eaten themselves. They have a few tricks. The most famous is autotomy: a harvestman can shed a leg if a predator grabs it. The detached leg continues to twitch for several minutes, potentially distracting the predator while the harvestman escapes. They can survive and function with fewer than eight legs, though they become less efficient at moving and sensing their environment.

Less well-known is their chemical defense. Harvestmen have scent glands on the front part of their body that can spray noxious secretions when disturbed. In one well-studied species, Rilaena triangularis, these glands emit a directed jet of fluid containing mainly 1,4-benzoquinone along with 1,4-naphthoquinone and octanoic acid.⁵ Benzoquinones are irritating compounds that can deter birds, ants, and other predators. The secretion smells pungent to human noses too. Different harvestman lineages produce different chemical cocktails, and these compounds are an active area of research because some are shared with beetles and millipedes that also use benzoquinone-based defenses, suggesting this is a broadly useful chemical strategy for small ground-dwelling invertebrates.

Some harvestmen also play dead (thanatosis), tuck their legs tight against their body to look like a small seed or pebble, or aggregate in large groups. Those shuddering clusters of dozens or hundreds of harvestmen you sometimes find under bridges or in caves are partly a defensive strategy: a mass of twitching legs can startle a predator, and the chemical secretions of many individuals together create a more effective cloud of deterrent.

What About Crane Flies

If you are in the UK or parts of Australia and someone says “daddy long legs,” they probably mean a crane fly. Crane flies are true flies in the family Tipulidae, and they have almost nothing in common with harvestmen or cellar spiders beyond having long legs. Adult crane flies eat very little. Some species sip nectar from flowers. Many species do not eat at all as adults and live only long enough to mate and lay eggs, typically just a few days.

The larvae, called leatherjackets, are the stage that does serious eating. They live in soil and feed on decaying organic matter, roots, and grass. Leatherjackets can be significant lawn pests in wet climates, damaging turf by chewing through root systems. So if your question is really “what do crane flies eat that I should care about,” the answer is your lawn, but only in the larval stage. The gangly adults bouncing off your windows are essentially on a mission to reproduce before they die, not to find food.

Finding and Identifying Your Daddy Long Legs

A quick guide to figuring out which creature you are dealing with:

Harvestmen: One compact, oval body (no visible waist separating two body segments), two eyes on a raised bump on top of the body, no web, no wings, found outdoors in leaf litter, under rocks, on tree trunks, or in shady garden areas. If you look closely and the body appears to be a single unit rather than two segments joined by a narrow waist, it is a harvestman.
Cellar spiders: Two distinct body segments (a small head section and a round abdomen joined by a thin waist), eight eyes clustered in two groups of three with two in between, always associated with a messy cobweb, found indoors in basements, closets, and garages. If it is hanging upside down in a web and vibrates rapidly when you disturb it, that is a cellar spider.
Crane flies: Six legs (not eight), two wings, two tiny knob-shaped balancing organs behind the wings, looks like an oversized mosquito with a thin body and long trailing legs, attracted to lights at night, found outdoors or bumping around inside after flying through an open window. If it flies, it is a crane fly, and it is neither an arachnid nor dangerous.

All three are harmless to people. Harvestmen are beneficial decomposers and minor predators. Cellar spiders are effective household pest controllers. And adult crane flies are just briefly inconvenient visitors that are not even interested in your food.

Why Harvestmen Cluster Together

If you have ever peeled back a piece of bark or peeked under a bridge abutment and found a roiling mass of harvestmen, you have witnessed one of their more unusual behaviors. These aggregations can contain hundreds or even thousands of individuals packed tightly together, their legs interlocked. The clusters serve multiple purposes. In dry or hot conditions, huddling together reduces water loss from each individual’s body surface. In cold conditions, the mass retains heat slightly better than an isolated individual. And as mentioned in the context of their chemical defenses, the collective secretion of benzoquinones and other deterrent compounds from many scent glands at once creates a stronger chemical barrier against predators than any single harvestman could produce.

These clusters are not family groups or colonies. Harvestmen are not social in the way ants or bees are. The aggregations are loose and temporary, often forming at favorable roosting sites and dispersing each evening when individuals leave to forage. A single sheltered spot might attract the same group night after night, but the membership shifts, and there is no division of labor or cooperative behavior beyond the passive benefits of being near other bodies. The effect, from a predator’s perspective, is a quivering ball of legs and chemical irritants that is far less appetizing than a single isolated harvestman would be.

Harvestmen and Garden Ecosystems

Gardeners sometimes wonder whether harvestmen are helpful or harmful. The short answer is that they are mildly helpful and essentially never harmful to plants. Their diet of aphids, mites, small slugs, and insect eggs means they contribute to pest suppression, though not dramatically enough to replace any actual pest-control method. Their scavenging of dead insects and decaying organic matter contributes to decomposition. Their consumption of fungi may have subtle effects on fungal community composition in soil and leaf litter, though this is not well quantified.

Because harvestmen need moisture and shelter, you are more likely to find them in gardens with mulch, leaf litter, compost piles, and ground cover than in bare, dry landscapes. They are nocturnal foragers and spend daylight hours hiding. If you see one during the day, it has probably been disturbed from its resting spot. Providing ground-level habitat like rock piles, logs, or thick mulch encourages their presence, which, if you are the sort of person who likes having a diverse garden ecosystem, is a modest net positive. They will not damage your vegetables, and they might eat a few of the things that do.