The common name widow spiders is applied to members of the genus even though the males are not usually eaten after mating and can even go on to fertilize other females. The Black Widow spiders are well-known members of the genus. The female black widow’s venom is particularly harmful to humans (males almost never bite humans). The injection of venom from these species is a comparatively dangerous or lethal spider bite, resulting in the condition Latrodectism which is named for the genus.
Spiders of the genus Steatoda (also of the Theridiidae family) are often mistaken for widow spiders, and are known as false widow spiders. The false widow spiders are significantly less harmful to humans.
Along with the southern, western and northern black widows (Latrodectus mactans, Latrodectus hesperus and Latrodectus variolus) with the famed red hourglass, the gray or brown widow spiders (Latrodectus geometricus), and the red widow spiders (Latrodectus bishopi) (Preston-Malfham, 1998) are also found in the United States. But there are widow spiders on every continent of the world except for Antarctica. The single species occurring in Australia, Latrodectus hasselti, has Redback as one common name; African species of this genus are sometimes known as button spiders.
In common with other members of the Theridiidae family, the widow spiders construct a cobweb, i.e., an irregular tangle of sticky silken fibers. The black widow spider very frequently hangs upside down near the center of its web and waits there for insects to blunder in and get stuck. Then, before the insect can extricate itself, the spider rushes over to bite it and swathe it in a silken shroud. If the spider feels threatened it will normally let itself down to the ground on a safety line of silk just as fast as it can. As with other web-weavers, these spiders have very poor eyesight and depend mostly on vibrations reaching them through their webs to orient themselves to prey or warn them of larger animals that could injure or kill them. They are not aggressive, and most injuries to humans are due to defensive bites delivered when a spider gets unintentionally squeezed or pinched somehow. It is possible that some bites may result when a spider mistakes a finger thrust into its web for its normal prey, or in cases where a female is protecting an egg sac, but ordinarily intrusion by any large creature will cause these spiders to flee.
*Some of the cities that Awesome Pest Control in Utah has helped to remove Spiders from include: Alpine, Alta, American Fork, Birdseye, Bluffdale, Cedar Fort, Cedar Hills, Cedar Valley, Colton, Copperton, Cottonwood Heights, Draper, Eagle Mountain, Elberta, Elk Ridge, Emigration, Fairfield, Genola, Goshen, Herriman, Highland, Holladay, Kearns, Lehi, Lindon, Magna, Mapleton, Midvale, Millcreek, Murray, Orem, Payson, Pleasant Grove, Provo, Riverton, Salem, Salt Lake City, Sandy, Santaquin, Saratoga Springs, South Jordan, South Salt Lake, Spanish Fork, Springville, Taylorsville, Vineyard, West Jordan, West Valley City, White City and Woodland Hills.