Owl Pest Control
Cellar Spiders - Daddy Long Legs (Pholcus phalangioides)
Appearance
Cellar Spiders are pale yellow to light brown or gray hue. They have long thin legs with a tiny body (6-9mm in size). Their extremely long legs make these spiders appear much larger and give them their nickname of “daddy long legs”.
Habits
Cellar spiders are found in dark and damp places. They 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 produce extensive webbing in a relatively short time.
Threats
Cellar spiders are of no threat to humans. While they are commonly found in homes, they usually remain in one location. They do not bite.
Prevention
- Regular removal of cellar spiders with a vacuum cleaner or brush helps restrict their activity.
- Seal all cracks on the exterior of the home, especially around doors and windows, and use screens to prevent entry into homes.
- The use of yellow light bulbs for exterior lighting may reduce the number of spiders and other insects as they are typically attracted to brighter white-light sources.
- Lowering the humidity in basements, cellars and crawl spaces with the use of a dehumidifier or ventilation can discourage cellar spiders from living there.
Cellar spiders (Pholcus phalangioides) are one of the most common spiders found in Irish homes. Known colloquially as daddy long legs spiders, they are frequently confused with two other “daddy long legs” creatures — crane flies (the flying insects most Irish people know as daddy long legs) and harvestmen (spider-like arachnids that do not spin webs and have oval bodies). Cellar spiders are quite different from both: they are true spiders, spin tangled webs in corners, and are completely harmless to humans.
Identification
Cellar spiders are pale yellow to light brown or grey with an extremely small body (6-9mm) and very long, thin legs that can span up to 7cm. They hang upside down in their loose, irregular webs and vibrate rapidly when disturbed — a behaviour thought to make them appear blurry and harder for predators to target. Their webs are not cleaned but continuously added to, which can produce extensive cobwebbing in a short time.Are Cellar Spiders Dangerous?
No. Cellar spiders do not bite humans in normal circumstances. There is a popular myth that cellar spiders are among the most venomous spiders in the world but are harmless only because their fangs cannot penetrate human skin. This is not supported by evidence — their venom is no more toxic than that of other common house spiders, and they have no interest in biting humans. They are, if anything, beneficial — cellar spiders actively hunt and kill other spiders, including larger house spiders, catching them in their webs. A cellar spider in the corner of a room is doing no harm and may be reducing the number of other spiders present.Why Are They In My Home?
Cellar spiders prefer dark, damp environments — basements, cellars, garages, sheds, bathroom corners, and undisturbed cupboards. They typically remain in one location for long periods, adding to their web rather than moving around. They are more noticeable in autumn when they become more active and adult males move in search of mates.How to Reduce Cellar Spider Numbers
- Regular removal of webs with a vacuum cleaner or brush — removing the web discourages the spider from staying in that location
- Seal cracks around doors, windows, and the building exterior to reduce entry points
- Reduce humidity in basements and cellars using ventilation or a dehumidifier — dry conditions are less attractive to cellar spiders
- Use yellow or warm-white bulbs for exterior lighting — white light attracts insects which attract spiders
- Remove clutter from basements and garages that provides undisturbed harbourage
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