The Pholcidae are a family of araneomorph spiders, having fangs that point diagonally forward and cross in a pinching action. They are commonly known as cellar spider, daddy long-legs spider, carpenter spider, daddy long-legger, vibrating spider, gyrating spider, long daddy, and skull spider.
Daddy long legs spiders are easily recognized by their extremely long, skinny legs and small body. They are found in most urban areas, in particular houses. They make a thin, tangled web in sheltered positions where they are unlikely to be disturbed, such as under furniture, behind doors, in the corner of the ceilings, in sheds, in garages, and under decks. Their family contains over 1,800 individual species first described by Carl Ludwig Koch in 1850 and is divided into 94 genera or sub-families.
Pholcids are thin and delicate arachnids. The body, resembling the shape of a peanut, is approximately 0.08–0.39 inches in length, and the legs may be up to 1.97 inches long. They are gray to brown, sometimes clear, with banding or chevron markings.
They have cylindrical abdomens and eyes arranged in two lateral groups of three and two smaller median contiguous eyes. Arrangements of eight and six eyes both occur in this family. They have legs roughly 4 times as large as their bodies.
Some species of Pholcidae exhibit a threat response when disturbed by a touch to the web or entangled large prey. The arachnid responds by vibrating rapidly in a gyrating motion in its web, which may sometimes fall into a circular rhythm.
It may oscillate in tune with the elasticity of the web causing an oscillation larger than the motion of the spider’s legs. Although they do eat insects, certain species of these spiders invade the webs of other spiders to eat the host, the eggs, or the prey.
In some cases the spider vibrates the web of other spiders, mimicking the struggle of trapped prey to lure the host closer. After mating the female uses her long ovipositor to lay her eggs in a cleft in the soil. The eggs hatch with the warmth of spring. Many species of daddy longlegs live less than one year, though some may survive for several years.
I almost always see them in my bathrooms. There is an urban legend that daddy long legs spiders have the most potent venom of any spider but that their fangs are either too small or too weak to puncture human skin.
According to Rick Vetter of the University of California, Riverside, the daddy long-legs spider has never harmed a human, and there is no evidence that they are dangerous to humans. On the Mythbusters TV show, hosts Jamie Hyneman and Adam Savage debunked this myth.
They injected some black widow and daddy long legs venom into a mouse. The black widow venom had a stronger reaction. Then Adam let a daddy long legs spider bite him and it did manage to break its fangs through his skin, causing a slight burning sensation. No other effect was made.
- Carl Ludwig Koch (September 21, 1778 – August 23, 1857) was a German entomologist and arachnologist. He was responsible for classifying a great number of spiders, including the Brazilian whiteknee tarantula and common house spider. He was born in Kusel, Germany, and died in Nuremberg, Germany. Carl Ludwig Koch was an inspector of water and forests. His principal work Die Arachniden (1831–1848) (16 volumes) was commenced by Carl Wilhelm Hahn (1786–1836). Koch was responsible for the last 12 volumes. He also finished the chapter on spiders in Faunae insectorum germanicae initia oder Deutschlands Insecten [Elements of the insect fauna of Germany] a work by Georg Wolfgang Franz Panzer (1755–1829). [Back]
- Rick Vetter, retired entomology research associate and spider expert. His research interests include the psychological effects that spiders have on the humans they terrorize. [Back]