Comb-footed spiders (Theridiidae)
The comb-footed spiders, also known as cobweb spiders and tangle-web spiders (family Theridiidae) are a large group (over 2000 species in nearly 80 genera) of haphazard web-builders found throughout the world. The characteristics of this family of spiders are that they build tangled, haphazard webs and have a comb of serrated bristles (setae) on the feet of the forth leg. The family includes the genus Latrodectus, the notorious widow spiders
The Common house spider, sometimes called the American house spider, is an extremely common spider in North America, as its name suggests. There are several species of this genus, Achaearanea, sharing many common features. They build their tangled web in secluded locations, which can also house eggs contained in one or more spherical sacs. Their behavior on webs is quiet and efficient. They are generally dull in appearance, with patterns consisting of brown shades for coloration. Their average body size is a quarter-inch long. These traits combined allow the spiders to blend into the background and escape notice.
These spiders are not aggressive. They are not known to bite people frequently, nor is their venom known to be dangerous to human beings. When removed from their webs their poor vision renders them helpless. Their only concern seems to be to find and return to their own web or build another one. They do not wander around inside houses except to find a secure place to build a web. Some people tend to fear all arachnids, but since these spiders in particular are harmless and their diet consists of pests such as flies and mosquito, tolerating their presence in homes is beneficial.
Many species of Common house spider share a body shape and size that makes them similar to widow spiders, which have venom that is classified as very dangerous. The widows can be distinguished from the harmless house spider by their glossy black color, with their bodies usually featuring a red hourglass or other marking.