Pholcus phalangioides

(Fuesslin, 1775)

Long-bodied Cellar Spider, Cosmopolitan Cellar Spider, Daddy Long-legs Spider

Pholcus phalangioides is a long-legged cellar spider native to Asia that has become through human association. Females reach about 7-8 mm body length with legs 5-6 times longer; males are slightly smaller at 6-10 mm. The is notable for building loose, irregular webs in dark indoor spaces and for its specialized predatory including web invasion and . It preys on other spiders—including dangerous species such as redbacks—and exhibits a distinctive whirling defense against . Despite common misconceptions, its bite is harmless to humans.

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Pronunciation

How to pronounce Pholcus phalangioides: /ˈfɔlkʊs fəˌlæŋɡiˈɔɪdiːz/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from harvestmen (Opiliones) and crane flies ()—which share the 'daddy long-legs' —by eight legs (harvestmen also have eight but body, crane flies have six), two distinct body segments, and silk production. Separated from other Pholcidae by eight (some pholcids have six) and specific eye arrangement. Differs from the Marbled Cellar Spider (Holocnemus pluchei) by body patterning and dome-shaped web architecture in the latter.

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Habitat

Strongly ; primarily inhabits dark, quiet indoor environments including cellars, attics, garages, caves, and building corners. Requires warmth and avoids cold outdoor conditions in temperate regions. Outdoors, occurs in caves and rock crevices in suitable climates.

Distribution

Native to Asia; now in temperate and tropical regions worldwide. Established across Europe, North America, Australia, and other continents through human-mediated . Distribution closely tied to human buildings, with genetically isolated and showing low intrapopulation variation but significant interpopulation differentiation.

Seasonality

Active year-round in suitable indoor environments; may live up to two years or more. Fall appears to be a period of increased male wandering in search of mates in at least some .

Diet

of insects, other spiders, and small . Notable araneophage that invades webs of other spiders to prey on occupants and their . Uses —creating specialized vibrations—to lure prey spiders. Will attack prey at web edges by leaning out and shooting silk while clinging with only two legs. Engages in when prey is scarce.

Life Cycle

Development includes multiple molting stages (instars) over approximately one year to maturity. Males show two subadult stages: first ~4 weeks before final , second ~2 weeks before. begins weeks before maturity and continues throughout life. Adults may live two years or more post-maturity. Females carry sacs in jaws to protect from ; spiderlings briefly ride on mother after hatching.

Behavior

Builds loose, horizontal, irregular webs often intertwined with conspecifics. Exhibits 'whirling' defense—rapid body gyration while legs remain fixed on web—when disturbed; duration varies by threat level (short for human touch, hours to days for jumping spiders). Males perform elaborate courtship: abdominal vibrations, web tapping, leg jerking, and direct female leg tapping. Males remove rival sperm before depositing their own. Communication primarily tactile and chemical via .

Ecological Role

that helps control of other spiders and insects; considered beneficial where it preys on medically significant spiders such as redbacks. Serves as prey for jumping spiders (Salticidae), particularly Portia fimbriata, which uses to subdue it.

Human Relevance

Considered beneficial household controlling pest insects and dangerous spiders. Harmless to humans despite common misconceptions; bite produces only mild, transient sting. Subject of biomedical research: silk contains antimicrobial compounds active against drug- (Listeria monocytogenes, E. coli, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa) and has potential for wound healing applications. Dragline silk has been investigated for biological imaging applications.

Similar Taxa

Misconceptions

Cannot bite humans due to short fangs: false—fangs (~0.25 mm) can penetrate human (~0.1 mm), but bites are rare and medically insignificant. Most venomous spider but fangs too short to bite: false—venom has weak effect even on insects and negligible effect on mammals. 'Daddy long-legs' name causes persistent confusion with harvestmen and crane flies.

More Details

Silk gland specialization

Uses multiple silk types in combination for different ; only aerial lines rely on single silk type. draglines show highest mechanical performance. Mixed silk bundles achieve toughness comparable to araneid orb-weaver silks through different evolutionary .

Sperm competition

Second males have reduced copulation duration, limiting sperm displacement; first male sperm typically predominates despite female multiple mating.

Genetic structure

Human-mediated created small, isolated with strong founder effects and geographic isolation-driven genetic drift rather than .

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Sources and further reading