Cellar Spider

Pholcus phalangioides

cellar spider

The cellar spider or daddy longlegs (Pholcus phalangioides), also known as the skull spider due to its cephalothorax looking like ahuman skull, is a spider of the family Pholcidae. Females have a body length of about 9 mm; males are slightly smaller. Its legs are about 5 or 6 times the length of its body (reaching up to 7 cm of leg span in females). Its habit of living on the ceilings of rooms, caves, garages or cellars gives rise to one of its common names. In Australian homes, they are considered beneficial because it is sometimes believed they will kill and eat the venomous Redback spider.

This is the only spider species described by the Swiss entomologist Johann Kaspar Füssli who first recorded it for science in 1775. Confusion often arises over its common name, because "daddy longlegs" is also applied to two other unrelated arthropods: the harvestmanand the crane fly.

Pholcus phalangioides has the habit of shaking its web violently when disturbed as a defence mechanism against predators. They can easily catch and eat other spiders (even those much larger than itself, such as Tegenaria duellica), mosquitoes and other insects, and woodlice. When food is scarce, they will prey on their own kind.

Because they originally came from the tropics, these spiders do not seem to be aware of seasonal changes and breed at any time of the year. The female holds the 20 to 30 eggs in her pedipalps. Spiderlings are transparent with short legs and change their skin about 5 or 6 times as they mature.


An urban legend states that Pholcidae are the most venomous spiders in the world, but because their fangs are unable to penetrate human skin, they are harmless to humans. However, recent research has shown that pholcid venom has a relatively weak effect on insects. In the MythBusters episode "Daddy Long-Legs" it was shown that the spider's fangs (0.25mm) could penetrate human skin (0.1mm) but that only a very mild burning feeling was felt for a few seconds.


Cellar spiders build loose, irregular, tangled webs in corners. They hang upside down on the underside of the web. The webs are not cleaned but instead a new web is continually added. This habit can result in extensive webbing in a relatively short time.


The spiders and their webs are usually found in dark and damp places, such as cellars, basements, and crawl spaces. They can also be found in the corners of garages, sheds, barns, and warehouses, on eaves, windows, and ceilings, and in closets, sink cabinets, and bath-traps. Cellar spiders seem to fare better in areas with higher relative humidity,


Cellar spiders do not pose a threat to humans. While they are commonly found in homes, they usually stay in one place. They are not known to bite. Urban legend has it that their venom is of the most deadly of spiders, but their weak mouthparts keep them from injecting venom into humans. While it is correct that they cannot successfully bite, their venom is not very potent.


Seal cracks on the outside of the home, especially around doors and windows, and use screens to prevent entry into homes. Using yellow light bulbs for exterior lighting may reduce the number of spiders and other insects as they are typically attracted to white-light sources. Additionally, lowering the humidity in basements, cellars and crawl spaces with the use of a dehumidifier or ventilation can discourage cellar spiders from living there.


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