Pholcus phalangioides

Lore & Background

Its common name of 'daddy long-legs' should not be confused with harvestmen (Opiliones) or crane flies (Tipuloidea). Females have a body length of about 8 mm, while males tend to be slightly smaller, and the legs are on average 5 or 6 times the length of the body. The species is sexually dimorphic, with females slightly larger than males. The bodies are translucent, grey-pale brown, with a dark spot on the back of the prosoma and dark blurred spots on the dorsal side of the opisthosoma. Unlike some other Pholcidae, it has eight eyes.

Reader's Guide

Pholcus phalangioides is significant as a widespread synanthropic species whose geographic distribution has been shaped by human activity. Its preference for warmer indoor habitats has allowed it to spread to most temperate countries on every continent, though its original native range is uncertain, with recent authorities regarding it as only native to Asia. The species is considered beneficial because it preys on other spiders, including dangerous species like redback spiders, and is harmless to humans. Its population structure is heavily influenced by human-made buildings, leading to small, isolated populations where genetic drift, particularly the founder effect, plays a major role. This results in low genetic variation within populations but significant differentiation between populations. The species has also been noted for potential medicinal use of its silk. Its defensive behavior includes whirling, a gyration of the body, which can last from short durations to several hours or days depending on the predator.

Did You Know?

• Females have a body length of about 8 mm, while males average about 6 mm, and their legs are roughly 5 to 6 times the length of the body.
• This spider is known to be harmless to humans and preys on other spiders, including dangerous species such as redback spiders.
• Its primary defense strategy is whirling, where it swings its body in a circle while its legs remain fixed on the web.