Summary
The long-bodied cellar spider is the source of the persistent 'most venomous spider in the world' myth. The claim is false: while the spider does bite humans, its venom is mild and has no documented medical significance. The species is also frequently confused with the harvestman (true daddy long-legs, Opiliones), which is not a spider at all.
Quick answers
- Is Cellar Spider dangerous to humans?
- No. Current evidence does not link cellar spider bites to serious medical outcomes in healthy adults.
- How big is an adult cellar spider?
- Adult female body length is 7–10 mm; males are 6–9 mm. Leg span reaches 40–70 mm.
- Where does Cellar Spider live?
- Indoors in undisturbed corners - basements, garages, attics, behind furniture. Established U.S. populations occur in 1 states.
- What does Cellar Spider eat and when is it active?
- Insects and other spiders - notably preys on widow spiders, house spiders, and even larger species by exploiting its long legs to wrap prey from a safe distance. Sedentary on the web. Eats other spiders, including widows.
Identification
- Body 7–10 mm with extraordinarily long thin legs (leg span 40–70 mm)
- Pale tan or gray translucent body
- Cylindrical (not spherical) abdomen
- Vibrates rapidly in the web when disturbed (a defensive blur)
- Loose, untidy web in upper corners
Morphometrics
| Measurement | Female | Male |
|---|---|---|
| Body length | 7–10 mm | 6–9 mm |
| Leg span | 40–70 mm | - |
| Lifespan | 2–3 years | - |
| Trait | Value |
|---|---|
| Web type | Loose, irregular tangle web in undisturbed corners. The spider vibrates rapidly when disturbed. |
| Eye arrangement | Eight eyes in two lateral triads with two small median eyes between. |
| Eggs per sac | 20–35 |
| Egg sacs per year | 3–5 |
Geographic range
Native range: Cosmopolitan synanthrope, likely native to the subtropical Old World; established worldwide in heated buildings.
U.S. states with established populations: All 50 U.S. states (indoors).
State pages covering Cellar Spider
AlabamaAlaskaArizonaArkansasCaliforniaColoradoConnecticutDelawareFloridaGeorgiaHawaiiIdahoIllinoisIndianaIowaKansasKentuckyLouisianaMaineMarylandMassachusettsMichiganMinnesotaMississippiMissouriMontanaNebraskaNevadaNew HampshireNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaOhioOklahomaOregonPennsylvaniaRhode IslandSouth CarolinaSouth DakotaTennesseeTexasUtahVermontVirginiaWashingtonWest VirginiaWisconsinWyoming
Habitat & behavior
Habitat: Indoors in undisturbed corners - basements, garages, attics, behind furniture.
Activity: Sedentary on the web. Eats other spiders, including widows.
Diet: Insects and other spiders - notably preys on widow spiders, house spiders, and even larger species by exploiting its long legs to wrap prey from a safe distance.
Venom & medical significance
| Venom property | Value |
|---|---|
| Type | Not medically significant |
| LD₅₀ | Not established |
| Note | Fangs are capable of penetrating human skin, but the venom causes only a brief burning sensation in self-experiments. |
Bite symptoms & first aid
Symptoms
- Mild, brief stinging sensation if at all; no medical significance
Commonly confused with
- Harvestman / true daddy long-legs (Opiliones - not a spider)
- Brown recluse (because of long legs)
Key facts
- The 'most venomous spider' claim popularized by daddy long-legs urban legend has no scientific basis - the species has been tested and is not medically significant. [1]
- Cellar spiders prey on other spiders, including black widows and brown recluses, and are sometimes encouraged in basements as a form of biological control. [2]
Sources
- [1]Cellar Spiders - University of California Statewide IPM Program. Accessed 2026-06-14.
- [2]Daddy Long-Legs Myth - University of California, Riverside Spider Research. Accessed 2026-06-14.