Cheiracanthium
Cheiracanthium, commonly called yellow sac spiders, is a genus of araneomorph spiders in the family Cheiracanthiidae, and was first described by Carl Ludwig Koch in 1839. They are usually pale in colour, and have an abdomen that can range from yellow to beige. Both sexes range in size from . They are unique among common house spiders because their tarsi do not point either outward, like members of "Tegenaria", or inward, like members of "Araneus"), making them easier to identify. The name is a reference to the backwardly directed process on the cymbium of the male palp. The species epithet  is derived from the Greek , meaning "hand", and "Acanthium", a genus of thorny-stemmed plants. Venom. Though they are beneficial predators in agricultural fields, they are also known to be mildly venomous to humans. Painful bites may be incurred from species such as "C. punctorium" in Europe, "C. mildei" in Europe and North America, "C. inclusum" in the Americas, "C. lawrencei" in South Africa and "C. japonicum" in Japan. "Cheiracanthium" venom is purportedly necrotic, and can cause pain, swelling, and lesions in humans, but the necrotic nature and severity of its bite has been disputed. A study of twenty confirmed  Cheiracanthium bites in the United States and Australia found that none resulted in necrosis. Some of these spiders are attracted to the smell of volatiles in gasoline. An unspecified "Cheiracanthium" species is reportedly attracted to the smell of petroleum and has caused problems by weaving webs inside the canister vent of particular models of Mazda vehicles, resulting in blockages and build-up of pressure that could potentially cause fuel leakage from the fuel tank and an increased risk of fire. Mazda issued a voluntary recall of Mazda 6 models built between 2010 and 2012, to fit them with software which  would alert drivers if problems were developing. Species. "Cheiracanthium" is primarily an Old World genus, with many species found from northern Europe to Japan, from Southern Africa to India and Australia. The only known species in the New World are "C. inclusum" and "C. mildei". While the former also occurs in Africa and Réunion, the latter is found in the Holarctic region and Argentina. They can also be found in the lower mainland of British Columbia, Canada. The genus is quite diverse in Africa and at least three or four species are known to occur in Egyptian cotton fields alone . it contains 212 species, found in the Caribbean, South America, Oceania, Europe, Central America, Africa, Asia, North America, and on Saint Helena: