Pholcidae

C. L. Koch, 1850

cellar spiders, daddy long-legs spiders, carpenter spiders, vibrating spiders, gyrating spiders

Pholcidae is a large of araneomorph containing over 2,000 across 94+ . Members are commonly known as cellar spiders or daddy long-legs spiders due to their extremely long, thin legs and tendency to inhabit dark, undisturbed spaces. The family exhibits remarkable diversity in use, from caves and tropical forests to human dwellings, with some species showing specialized including troglomorphism and communal web-sharing. Several species have become globally distributed through human transport, notably Pholcus phalangioides.

Spermophora senoculata by (c) Eleftherios Katsillis, some rights reserved (CC BY), uploaded by Eleftherios Katsillis. Used under a CC-BY license.

Psilochorus simoni by (c) Lek Khauv, some rights reserved (CC BY), uploaded by Lek Khauv. Used under a CC-BY license.

Psilochorus simoni by (c) Tom, some rights reserved (CC BY), uploaded by Tom. Used under a CC-BY license.

Pronunciation

How to pronounce Pholcidae: /ˈfɒlsɪdiː/

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

Identification

Distinguished from other long-legged by the unique pattern: two triads of three eyes each, with zero or two small . Differs from () by having two distinct body rather than one body. Separated from spitting spiders (Scytodidae) and recluse spiders (Sicariidae) by having eight eyes (versus six) and lacking the highly convex of spitting spiders. Some (Modisimus, Spermophora, Spermophorides) have only six eyes and require careful examination of eye arrangement pattern. specimens often cannot be identified to due to undeveloped .

Images

Habitat

Highly diverse: natural include caves, rock crevices, under loose bark, leaf litter, and dense vegetation in tropical and subtropical regions. Many are , inhabiting buildings in undisturbed areas such as high corners, attics, cellars, and window frames. Cave-dwelling species show range from fully troglomorphic (eyeless or reduced ) to non-troglomorphic forms. Communal web-building occurs in some species, with up to 15 individuals sharing contiguous webs. appears critical for many species, with webs built to avoid direct sunlight.

Distribution

Global distribution in tropical and subtropical regions; present on all continents except Antarctica. Mexico contains the highest diversity of troglomorphic . Several species have become through human-mediated , notably Pholcus phalangioides. established in Europe, North America, and elsewhere. faunas show high in the Venezuelan Andes, Coastal Ranges, Guyana Highlands, and Sri Lanka.

Diet

on . Primary includes and other . Several are documented to invade webs of other spiders to consume the , , or cached prey; some vibrate foreign webs to mimic struggling prey and lure the resident spider. Known to prey on medically significant spiders including redback spiders (Latrodectus), huntsman spiders, house spiders, and Tegenaria funnel weavers. May provide of hobo spider in some regions. Prey capture relies on web structure rather than adhesive —prey become entangled in irregular web architecture and are rapidly wrapped in silk.

Life Cycle

Developmental stages include , , and . Females of some wrap eggs loosely in thin sheets and carry them beneath the body. Immature specimens typically cannot be identified to species due to undeveloped genital structures. Sexual maturity marked by fully developed in males and or in females depending on .

Behavior

Web-building: construct irregular, three-dimensional, non-sticky webs. Hang inverted in webs when at rest. Threat response: rapid gyrating or vibrating motion when disturbed, potentially to confuse , signal rivals, or further entangle — that has led to 'vibrating ' . If disturbance continues, retreat to corners or drop from web to escape. Some use alternating gait (leg movement pattern) with documented variations. Communal web-sharing documented in Holocnemus pluchei and likely other species, with individuals competing for prey but rarely engaging in prolonged conflict. Some species employ by vibrating webs of other spiders.

Ecological Role

in diverse including caves, forests, and agroecosystems. Documented fluctuations in cocoa agroecosystems in Mexico, with Pholcus in lower and middle zones during windy seasons. Potential agents for pest and in urban and agricultural settings. on venomous spiders including widow spiders, suggesting possible role in regulating dangerous populations.

Human Relevance

Common household inhabitants globally; generally regarded as due to on other including pest and venomous . Not medically significant: capable of biting humans but is not toxic to humans. (, hooked structure) can penetrate skin but bites produce only mild, short-lived burning sensation. Subject of persistent urban legend falsely claiming 'most potent venom' but inability to bite humans—debunked by direct testing showing venom weak relative to other spiders and fangs capable of skin penetration. Some produce allergenic (arginine kinase in Holocnemus pluchei) with potential to induce asthma. Occasionally intercepted in international commerce, requiring identification for regulatory purposes.

Similar Taxa

Opiliones (harvestmen)Share 'daddy long-legs' and long thin legs, but have single body and only one pair of ; not at all.
Scytodidae (spitting spiders)Similar body plan with long legs and six in some Pholcidae , but have highly convex housing enlarged glands and spit sticky to capture .
Sicariidae (recluse spiders)Share six-eyed condition with some Pholcidae and similar preferences, but have distinct triad arrangement, violin-shaped marking on , and medically significant .

Misconceptions

The most pervasive misconception is the urban legend that daddy long-legs possess the most toxic of any spider but cannot bite humans due to small or weak . This is false: their venom is relatively weak, their fangs can penetrate human skin, and bites cause only minor effects. The legend may stem from their documented ability to kill venomous spiders like black widows, leading to erroneous assumptions about their own . and , also called 'daddy long-legs,' lack venom entirely, compounding confusion.

More Details

Taxonomic complexity

Pholcus, the largest , was substantially revised in 2018 with nine new genera erected from former Pholcus groups based on molecular . The continues to yield numerous new species descriptions, with 43 new Venezuelan species described in 2020 alone.

Cave adaptation

Of 473 cave-dwelling , only 86 show troglomorphic features (reduced or absent , elongated appendages). Most troglomorphic species belong to two (Modisiminae, Pholcinae), reflecting evolutionary concentration of microhabitat shifts in these lineages.

Female genital dimorphism

Pholcidae contains the first documented case of female genital in animals, highlighting potential under- of such variation due to taxonomic on genital characters for identification.