The spiders with notably long, thin legs you’re most likely encountering are cellar spiders, members of the family Pholcidae. These are true spiders, and they’re among the most common household arachnids worldwide. But “spiders with long legs” is also a phrase that pulls in two lookalikes that aren’t spiders at all: harvestmen and crane flies. Here’s how to tell them apart and what you actually need to know about each one.
Cellar Spiders: The Most Common Long-Legged Spider
Cellar spiders have legs that are many times longer than their bodies, which gives them a fragile, almost wispy look. Their bodies measure just 2 to 10 millimeters long (roughly the size of a grain of rice to a pencil eraser), but their leg span can make them appear much larger. They range in color from light tan to grayish-brown, and females tend to be noticeably bigger than males.
One species in particular, Pholcus phalangioides, has spread across the globe by hitching rides in human buildings and cargo. If you’ve seen a delicate, almost translucent spider hanging upside down in a messy, irregular web in your basement, garage, or a quiet corner of a room, that’s almost certainly a cellar spider. They have two distinct body segments (a front section and a separate abdomen), eight eyes in most species, and they produce silk and build webs. When disturbed, they’ll often vibrate rapidly in their web, bouncing so fast they become a blur. This is a defense mechanism meant to confuse predators.
Cellar spiders are genuinely useful housemates. They eat mosquitoes, flies, and even other spiders. They’re not aggressive toward people, and despite the persistent myth, they are not dangerously venomous.
The “Deadliest Venom” Myth, Debunked
You’ve probably heard the claim that daddy longlegs are the most venomous spiders in the world but can’t bite humans because their fangs are too short. This is false on both counts. According to researchers at the University of California, Riverside, there is no scientific evidence that cellar spider venom is especially toxic. No toxicological studies have tested pholcid venom on any mammalian system, and there are no documented cases of a cellar spider bite causing a harmful reaction in a person.
Their fangs are indeed short, with a pincer-like structure called “uncate” fangs. But brown recluse spiders have a similar fang structure and can obviously bite humans. So the “too short to bite” claim doesn’t hold up either. The bottom line: cellar spiders are harmless, and there’s no hidden danger lurking behind those spindly legs.
Three Creatures Called “Daddy Longlegs”
Part of the confusion around long-legged spiders comes from the fact that three completely different creatures all get called “daddy longlegs” depending on where you live. Knowing the differences helps you identify what you’re actually looking at.
Cellar Spiders (Pholcidae)
True spiders with two distinct body segments, eight eyes, silk-producing spinnerets, and venom glands. They build webs and live in dark, sheltered spaces. These are the ones you find indoors.
Harvestmen (Opiliones)
These are arachnids but not spiders. The easiest way to tell them apart from cellar spiders: harvestmen look like they have a single oval body. Their front and back sections are fused together with no visible “waist” or constriction between them. They have only two eyes (centered on top of their body), produce no silk, build no webs, and have no venom glands at all. They’re completely harmless and are typically found outdoors in leaf litter, gardens, and under rocks.
Crane Flies (Tipulidae)
Not even arachnids. Crane flies are insects with six legs (not eight), a pair of wings, and a body that looks like an oversized mosquito. They don’t bite or sting. Adults are short-lived and mostly exist to reproduce. If the “spider” you’re looking at is flying, it’s a crane fly.
Quick Identification Guide
- Two body segments, web, eight eyes: cellar spider (true spider)
- One oval body, no web, two eyes: harvestman (not a spider)
- Six legs, wings, flying: crane fly (an insect)
Other True Spiders With Long Legs
Cellar spiders aren’t the only long-legged spiders you might encounter. Several other spider families produce species with notably elongated legs, though cellar spiders are the ones most people are asking about.
Orb weavers in the genus Tetragnatha, sometimes called long-jawed spiders, have stretched, stick-like bodies and long legs adapted for gripping their webs near water. Garden spiders and some wolf spiders can also appear leggy relative to their body size, though their legs tend to be thicker and more muscular than the thread-thin limbs of cellar spiders. If the spider you’re looking at has robust legs and isn’t hanging upside down in a messy web, it’s likely something other than a pholcid.
Managing Cellar Spiders Indoors
Cellar spiders are harmless and eat pest insects, so many people leave them alone. But if the webs are becoming unsightly or you’d rather not share your basement, here’s what works.
Regular cleaning is the single most effective strategy. A vacuum cleaner or broom removes spiders, webs, and egg sacs in one pass. Destroying egg sacs matters because each one can contain hundreds of young spiders. Cellar spiders prefer quiet, undisturbed spaces like closets, garages, basements, and attics. Reducing clutter in these areas makes them far less appealing as habitat.
To prevent new spiders from moving in, seal the entry points. Install tight-fitting window screens and door sweeps. Trim shrubs, vines, and tree branches that touch the house, since these act as bridges from outdoors. Move firewood and stacked items away from your foundation. At exterior doors, switching to yellow or sodium vapor light bulbs helps too. These attract fewer night-flying insects, which in turn means fewer spiders showing up to hunt.
For persistent problems, a perimeter insecticide spray around door thresholds, foundation vents, garage entrances, and the base of siding can reduce spider entry. These treatments typically need reapplication monthly or every other month during warmer seasons.