Cellar Spider, Daddy Long-Legs Spider, Skull Spider
Pholcus phalangioides
Family Pholcidae, Order Araneae. Key family characteristics include extremely long, delicate legs, a small oval or fused-looking cephalothorax and abdomen, and the habit of vibrating rapidly when disturbed.
Physical Description
The spider has a small, pale, pear-shaped or oval abdomen and a somewhat rounded, translucent cephalothorax. The cephalothorax features a distinctive dark marking near the center that vaguely resembles a human skull, which gives it one of its common names. The body texture is smooth and delicate, with extremely long, thin legs that are disproportionate to the tiny body.
Size Estimate
Body length is typically around 7 to 10 millimeters, while the leg span is remarkably wide, often reaching 5 to 7 centimeters. This specimen appears to be a typical adult.
Coloration & Markings
Pale grayish-tan, light brown, or yellowish overall with translucent qualities. The cephalothorax features a darker median pattern, and the abdomen may show faint, pale grey spots or chevrons, though they are often quite subtle or uniform.
Web Type
Irregular, messy tangle webs built in corners of ceilings, cellars, basements, and dark crevices. The webs lack sticky glue and rely on a loose three-dimensional mesh to trap wandering insects.
Eye Arrangement
Pholcids typically possess eight eyes arranged in three groups: a triad on each side and a pair of smaller median eyes situated on a raised tubercle in the middle, which is characteristic of the family.
Leg Characteristics
Extremely long, thread-like, and delicate legs with slight darker banding near the joints. They lack heavy spination but possess specialized claws for manipulating silk. When at rest, the legs are spread wide across the web or surface.
Venom & Safety Information
Venom Information
Neurotoxic venom tailored specifically for small arthropods and invertebrate prey. The venom has virtually no effect on human physiology due to the spider's tiny chelicerae and low venom volume.
Medical Significance
Harmless to humans. Despite urban legends regarding extreme toxicity, they lack the medical significance, fangs capable of piercing human skin easily, or venom potency to pose any threat to people.
Safety Recommendations
No safety measures needed as they are completely harmless. If unwanted in living areas, they can be gently scooped up in a cup and relocated to a garage or shed.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution, found worldwide in temperate and tropical regions, almost exclusively in human dwellings, outbuildings, cellars, caves, and sheltered dark spaces where humidity is moderate.
Behavior & Temperament
Docile and completely harmless to humans. When disturbed or threatened, it initiates a rapid bouncing or vibrating defense mechanism within its web, making it appear blurry to potential predators.
Diet & Prey
Generalist insectivore feeding on small crawling and flying insects. Famously known to hunt and consume other spiders, including much larger and potentially dangerous species like redbacks or hobo spiders, using rapid silk-wrapping techniques.
Seasonal Activity
Active year-round indoors where climate is controlled, with mating occurring primarily during the warmer spring and summer months.
Description
Often mistaken for harvestmen due to its slender frame, the cellar spider is a permanent and harmless resident of human habitations worldwide. Master architects of chaotic corner webs, these delicate arachnids serve as tireless pest controllers, keeping basements and dark crevices free of flies, mosquitoes, and even other spiders.
Key Features
Extremely long, thin legs paired with a tiny, elongated or oval abdomen, pale tan coloration, skull-like marking on the cephalothorax, and the characteristic rapid vibrating behavior when disturbed.
Similar Species
Opiliones (Harvestmen, which are arachnids but not true spiders, lacking a segmented waist and silk glands) and Phalangium opilio; cellar spiders can be distinguished by their segmented two-part body and web-building habits.
Life Cycle
Females carry their eggs in a loose, silken sac held directly in their jaws rather than attaching it to the web. Spiderlings hatch as miniature adults and undergo multiple molts over a lifespan that can exceed two years.
Ecological Importance
Acts as an effective natural pest control agent inside buildings and homes, regulating populations of nuisance insects and other arachnids without any chemical intervention.
Conservation Status
Not evaluated by the IUCN, but populations are extremely secure, widespread, and thriving globally alongside human infrastructure.
Interesting Facts
Cellar spiders have a reputation for being aggressive hunters of other spiders, famously defeating and consuming venomous widows and large house spiders by wrapping them in silk from a safe distance using their exceptionally long legs.
Photography Tips
Use macro lenses with good depth of field to capture the entire leg span while keeping the tiny body in focus. Diffused natural lighting or a ring flash helps highlight the translucent body textures without causing harsh glares.
Identified: 2026-09-18T06:56:43.278430