Cellar Spider, Daddy Long-Legs Spider, Skull Spider
Pholcus phalangioides
Family Pholcidae (Cellar Spiders), Order Araneae
Physical Description
The cellar spider possesses a small, oval cephalothorax and an elongated, cylindrical abdomen that tapers toward the rear. Its most striking physical traits are its exceptionally long, delicate, thread-like legs relative to its tiny body size. The exoskeleton has a smooth, semi-translucent texture, and the overall build is very fragile.
Size Estimate
Body length typically ranges from 7 to 10 millimeters, with a massive leg span stretching up to 5 to 7 centimeters. The specimen shown appears to be a fully grown adult.
Coloration & Markings
Coloration is predominantly pale grey, beige, or pale yellow. The cephalothorax often features a distinctive darker grey or brown marking near the center that vaguely resembles the shape of a human skull, giving rise to one of its alternative common names.
Web Type
Builds irregular, messy, three-dimensional tangle webs or sheet-like cobwebs in corners, basements, and dark crevices. The webs lack adhesive sticky silk; instead, prey becomes hopelessly entangled in the chaotic multi-directional threads.
Eye Arrangement
Features six to eight eyes grouped closely together on an elevated median tubercle on the cephalothorax. The arrangement typically consists of a prominent triad on each side with a smaller pair in the center (when eight are present).
Leg Characteristics
Legs are extremely long, very thin, and pliable. They lack prominent spination but possess specialized tarsal claws used for manipulating silk and prey. When disturbed, the spider engages in a rapid, blurring up-and-down oscillation within its web to evade visual detection.
Venom & Safety Information
Venom Information
Possesses a potent neurotoxin specialized for subduing insect and spider prey, delivered via tiny chelicerae. Despite an old urban legend claiming they are the most venomous spiders with mouths too small to bite humans, their venom is mild to humans and rarely medically significant.
Medical Significance
Harmless to humans. Their fangs are generally too short or weak to puncture human skin, and even if a rare bite occurs, it typically results in only mild, localized burning or redness that resolves quickly without medical intervention.
Safety Recommendations
No special safety measures are required as they are completely harmless. If desired, they can be gently relocated using a cup and a piece of paper rather than exterminated.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution found worldwide, highly associated with human habitations, particularly damp dark places such as cellars, basements, crawlspaces, garages, and the corners of quiet rooms.
Behavior & Temperament
Entirely docile and non-aggressive towards humans. When disturbed, it typically bobs or vibrates violently to become a blur to predators, or drops from its web to escape. It is a sedentary, nocturnal to crepuscular hunter.
Diet & Prey
Feeds on a wide variety of household insects and other arachnids, including notoriously aggressive species like the redback or hobo spider. It uses its extreme leg length to throw silk over dangerous prey before delivering a venomous bite.
Seasonal Activity
Active year-round indoors due to the climate-controlled environment of human buildings, with mating occurring throughout the warmer months and into autumn.
Description
The cellar spider is a familiar yet misunderstood household resident. With its remarkably elongated legs and translucent body hanging suspended upside down in a messy corner web, it serves as a silent, efficient guardian against home pests and even other more troublesome spiders.
Key Features
Extremely long, thread-like legs, an elongated cylindrical abdomen, pale coloration with a skull-like marking on the cephalothorax, and the characteristic defensive trembling behavior when disturbed.
Similar Species
Often confused with harvestmen (Opiliones) and crane flies (Tipulidae), which are not true spiders. True cellar spiders can be distinguished from harvestmen by their distinctly two-part segmented body rather than a single fused oval body.
Life Cycle
Females carry their pale, loosely bound egg sacs in their jaws rather than anchoring them to the web. Upon hatching, transparent spiderlings undergo multiple molts over several months. Adults can live for several years under favorable indoor conditions.
Ecological Importance
Acts as an effective biological pest control agent in domestic and agricultural buildings, helping to naturally manage populations of flies, mosquitoes, and other household arthropods.
Conservation Status
Not evaluated by the IUCN, but populations are extremely secure, widespread, and thriving globally due to their close association with human dwellings.
Interesting Facts
Cellar spiders are famous for invading the webs of other spiders, mimicking prey to lure the resident spider out, and then consuming them. They are also known to actively hunt and eat larger, potentially dangerous spiders like black widows.
Photography Tips
Photograph from a side or top-down angle using macro settings to capture the eye arrangement and cephalothorax markings. Ensure soft, diffused lighting to avoid harsh reflections on their glossy exoskeleton.
Identified: 2026-09-22T17:32:12.810365