Granddaddy Long Legs — Myths vs Facts About These Elusive Pests

Nov 15, 2019 | Pest Control

By Anna V., Editorial Lead — Pest Education · Last updated: April 2026

If you’ve ever walked into the garage, looked up at a ceiling corner, and spotted a tiny body with eight ridiculously long, thread-thin legs, you’ve almost certainly met a granddaddy long legs. At Northwest, we get asked about these spiders constantly, usually paired with the same two questions: Are they dangerous? and Why are there so many of them in my house? The answers are reassuring. Granddaddy long legs are among the most misunderstood pests in Georgia and the Southeast. They’re almost entirely harmless to people and pets, and they quietly eat a surprising number of the pests you actually do want gone.

Here’s what a granddaddy long legs actually is, why the name causes so much confusion, whether any version of the creature is dangerous, and how to handle them around the house.

The cellar spider is the most common “granddaddy long legs” you’ll see indoors in the Southeast.

What Is a Granddaddy Long Legs?

Here’s the part that surprises most people: “granddaddy long legs” isn’t one creature. It’s a regional nickname that gets applied to three very different animals. Knowing which one you’re looking at clears up most of the confusion.

1. Cellar Spiders (Family Pholcidae)

This is the one you almost certainly have in your home. Small slender body, eight legs that can span two or three inches, builds messy tangled webs in corners of basements, garages, attics, and crawl spaces. True spider, produces silk, produces a mild venom for hunting prey (not a threat to humans). In the Southeast, when someone says “granddaddy long legs,” this is the one they mean about 90% of the time.

2. Harvestmen (Order Opiliones)

Arachnid, but not a true spider. Fused body (no visible waist between head and abdomen), eight legs, no silk, no venom. You’ll usually see them outdoors in leaf litter, on stone walls, or under logs rather than indoors. Completely harmless.

3. Crane Flies (Order Diptera)

This one isn’t a spider at all. Crane flies are insects with six legs, two wings, and a mosquito-like body. They show up around porch lights on warm evenings and look like giant mosquitoes. They don’t bite. They don’t sting. They don’t carry disease. In some regions people call them “daddy long legs” or “mosquito hawks” (though they don’t eat mosquitoes either, despite the nickname).

Why the Name “Granddaddy Long Legs” Causes Confusion

The same name for three different creatures is how a lot of the venom myths got started. Someone will say harvestmen are “the most venomous spider in the world but can’t bite you,” a claim that’s wrong on three counts: harvestmen aren’t spiders, they don’t produce venom at all, and they can’t bite anything human-sized even if they tried. The claim probably got attached to cellar spiders at some point, mixed up with harvestmen, and turned into a schoolyard urban legend that won’t die. Cellar spiders do have venom. It’s adequate for a mosquito. A human isn’t on the menu.

Granddaddy Long Legs vs Other Long-Legged Creatures

Quick visual reference for telling the three apart:

Three different creatures all called “granddaddy long legs,” and only one is actually a spider.

Are Granddaddy Long Legs Venomous or Dangerous?

The short answer: no. The single most persistent myth is that granddaddy long legs are the most venomous spider in the world but physically can’t bite a human. Every piece of that claim is wrong.

• Cellar spiders do produce venom for hunting prey. Studies have measured its potency, and it’s nothing special. It’s on par with a mosquito’s saliva. A human bite, which is extraordinarily rare, causes at worst a mild, brief sting.
• Harvestmen don’t produce venom at all. They have no venom glands.
• Crane flies are insects with no venom, no stinger, and no biting mouthparts capable of breaking human skin.

None of the three is a medically significant pest. If you want an authoritative second opinion, the UGA Extension guide to common household spiders has a plain-language breakdown of the cellar spider and several other species you’re likely to see in a Georgia home.

Behavior & Habitat in Southeast Homes

Cellar spiders are the version you’ll encounter inside, so the rest of this post focuses on them.

Where They Live

Ceiling corners, basement joists, attic rafters, garage doorframes, crawl-space wall cavities, sheds, behind stored boxes. Anywhere dark, undisturbed, and with a steady supply of small insects passing through.

Webs

Messy, irregular, and loosely strung. Nothing like an orb weaver’s symmetrical web. The web isn’t sticky the way other spider webs are; cellar spiders rely on shaking the web to tangle prey further once something wanders in.

When You’ll See Them

In the Southeast, indoor cellar spider sightings peak in late summer and early fall. Two things are happening: the spiders are finishing a season of breeding, and they’re following their food (flies, gnats, mosquitoes) as those insects push deeper into homes ahead of cooler nights.

What Attracts Daddy Long Legs to Your Home?

If you suddenly have a lot of cellar spiders in the garage, it’s almost always one of three things:

• Other pests are thriving. Cellar spiders eat small flies, gnats, mosquitoes, moths, and other spiders. A heavy cellar-spider population usually means you also have a heavy small-insect population somewhere nearby, often in a basement drain, a damp crawl space, or an overwatered plant tray.
• Moisture. Cellar spiders like humid environments. Damp basements, leaky plumbing, unsealed crawl spaces, and humid attics are their favorite spots.
• Undisturbed clutter. Stacked boxes, stored furniture, piled lumber, and rarely-used corners let webs go untouched for weeks. Stability is more attractive to a cellar spider than food location.

Handle those three things and the spider population drops on its own, often faster than any treatment plan can drop it.

Are Granddaddy Long Legs Useful or a Nuisance?

Useful. It’s one of the few pests we tell customers to leave alone when they find one or two. Cellar spiders actively eat other cellar spiders, which self-limits their populations. More importantly, they eat mosquitoes, fungus gnats, and the occasional pantry moth. A small cellar-spider presence in the garage is pest control doing free work.

They cross the line into nuisance when you see large numbers indoors (20 or 30 in a single room), or when the webbing becomes impossible to keep ahead of. At that point it’s less about the spiders and more about whatever they’re eating.

A vacuum and a cup beats a chemical spray for cellar spiders 99% of the time.

How to Handle Granddaddy Long Legs in Your Home

Humane Removal

A cup and piece of paper is the classic method. Slide it over the spider, slide the paper underneath, and walk it outside. If there are webs you want cleared, a vacuum hose with a brush attachment handles them fast without hurting anything. Skip the pesticide spray for one or two spiders.

Prevention Tips

• Seal foundation cracks and gaps around doors, windows, utility penetrations, and garage side doors.
• Cut clutter in basements, attics, garages, and sheds. Less stable surface area means fewer web-building sites.
• Move outdoor lights away from entry points. Bright doorway lights pull in the insects cellar spiders eat, which then pulls in more cellar spiders.
• Fix leaks, run a dehumidifier in damp rooms, and address crawl-space moisture. Dry is unattractive.
• Trim shrubs back from the foundation. A three-foot clear zone around the house reduces harborage for both spiders and their prey.

When to Call a Professional

Most cellar-spider sightings don’t need a professional. Call Northwest if:

• You’re seeing 20+ spiders in a single room, or cobwebs reappear within days of clearing.
• You’re also seeing other small insects indoors, which means there’s a food-source issue we need to find.
• The spiders are appearing in the living area (kitchens, bedrooms, bathrooms) rather than just basements or garages, which often signals a moisture or entry-point issue.
• You’re uncomfortable with spider identification and want someone to confirm what you’re seeing isn’t a brown recluse or a widow.

(Not sure whether you’ve got a harmless cellar spider or something that needs attention? Request a free inspection and we’ll walk the home with you and ID what’s actually there.)

Frequently Asked Questions About Granddaddy Long Legs

Do granddaddy long legs eat mosquitoes?

Yes. Cellar spiders prey on small flying insects, including mosquitoes, gnats, moths, and even other spiders. A small cellar-spider population in a garage or basement is effectively free pest control for the kinds of insects you don’t want.

Can granddaddy long legs bite humans?

Bites are extraordinarily rare. Cellar spiders will only bite if trapped against skin, and the bite itself is mild (often compared to a mosquito sting). There’s no medical significance. Harvestmen and crane flies can’t bite humans at all.

Is a granddaddy long legs actually a spider?

It depends which one you’re looking at. Cellar spiders are true spiders. Harvestmen are arachnids but not spiders. Crane flies are insects. In the Southeast, if you see one indoors, it’s almost certainly a cellar spider.

How do you get rid of granddaddy long legs?

Humane relocation (cup and paper), vacuuming webs, sealing entry points, fixing moisture issues, and cutting clutter in storage spaces. Most homes don’t need chemical treatment for cellar spiders specifically. If populations stay high after those steps, the root cause is usually another pest issue feeding them.

Are granddaddy long legs poisonous to dogs?

No. Cellar spider venom isn’t harmful to dogs or cats. Harvestmen and crane flies don’t produce venom at all. If your dog eats one, there’s no cause for concern.

If cellar spiders keep coming back, the real issue is usually whatever else they’re eating.

Schedule a Spider Inspection Today

If cellar spiders are showing up faster than you can clear them, the problem usually isn’t the spiders. It’s whatever they’re eating. Northwest’s team handles the full workflow: identification, targeted treatment, and addressing the moisture or insect issues that draw spiders in. Most customers are surprised how much of the work happens outside the house.

• Schedule a Free Spider Inspection
• Learn About Our Pest Control Services
• Call (888) 466-7849. Same or next day pest treatments available across our Southeast service areas.