Pholcus phalangioides

Pholcus phalangioides is a spider in the family Pholcidae, with a small body and notably long, slender legs. Its coloring is usually pale yellow or light brown, with a large gray mark in the center of the cephalothorax; its body and legs are almost translucent and have fine gray hairs. The head is darker around the eyes. It has eight eyes: two small ones positioned in front of two groups of three larger eyes. In proportion to the body, the legs are usually five to six times its length. Females reach about 7–8 mm in body length; males are around 6 mm. Disproportionately long legs and a delicate body are visible traits that help identify it.

It usually occupies sheltered, dimly lit places, both in buildings—for example, basements, ceilings, corners, and spaces behind furniture—and in caves and beneath stones or ledges. It builds a broad, loose, irregular web, often spread horizontally or adapted to the shape of the site; it hangs upside down from it. The web serves to catch food: it eats small insects and other spiders, and it has been observed entering other spiders’ webs and taking advantage of them after capturing the resident spider. If its web is disturbed, it can make its body and the web vibrate rapidly, until it becomes difficult to distinguish. It hunts from an irregular web in a sheltered refuge.

Outside the mating period, it usually leads a solitary life, focused on capturing prey in its web. During courtship, males locate females by following chemical signals; during copulation, which can last several hours, they transfer sperm to the female’s genital opening. She can store it before the eggs are fertilized. After hatching, the young pass through a prenymphal stage: the mother watches over them for about nine days, until they molt and acquire the appearance of tiny spiders. They then leave the mother’s web and look for a place to build their own. The young disperse after their first molt, following this brief period of maternal care.