When everybody thinks of a spider, they probably think of this one. These spiders have a potent venom which sends thousands of people to the poison control center, But, fortunately, people rarely die from a bite. Latrodectus mactans is a broadly distributed genus of spiders with several species that together are referred to as true widows. This group is composed of those often loosely called black widow spider, brown widow spiders, and similar spiders. The Latrodectus genus of Black Widow spiders is found throughout the world, especially where grapes grow. They live in North America, South America, and southern Europe. They are also found in Australia, New Zealand, and South Africa. Latrodectus spider webs are commonly found near ground level inside storage sheds or in small holes and crevices around building foundations and outdoor furniture. Inside, webs may be found in crawl spaces and basements. Webs act as retreats for spiders, traps for prey and defenses against predators. According to a new study, latrodectus mactans and house spiders have comparable toxic compounds in their venom — but latrodectus mactans evolved faster and became far more dangerous. The common compounds are called latrotoxins; the latrodectus mactans, however, produces alpha-latrotoxin, which takes over an unlucky victim's nervous system. Alpha Latrotoxin causes all of the neuron's vesicles to dump out their neurotransmitters. And that's really what's painful. In other words, alpha-latrotoxin causes nerve cells to release all of their chemical signals at once, overwhelming the nervous system, and causing immense pain. Binding of alpha-latrotoxin to neuronal receptors results in massive release of acetylcholine (ACh) at the neuromuscular junction, resulting in profound muscle contraction. The symptoms of toxicosis relate to this neuromuscular activity and include muscle spasms, muscle pain, and abdominal rigidity. If you need to kill a latrodectus spider for your safety, it is completely fine by me. i am to inform you of these spiders, some of which will be cute like the orb-weaver, and others not so much, like the wolf spider. but i am not trying to scare anyone with the knowledge of the venom of these venomous spiders. Anyway, Latrodectus geometricus, commonly known as the brown widow, brown button spider, grey widow, brown black widow, house button spider or geometric button spider, is one of the widow spiders in the genus Latrodectus. As such, it is a 'cousin' to the more infamous Latrodectus mactans. Bites occur usually through accidental contact and pressing of the spider against the skin. Symptoms of a brown widow spider bite include a red mark at the bite site and some pain locally. The bite is not usually life threatening, and is considered less serious than a latrodectus mactans bite. The bite of the latrodectus geometricus is about the same as any non-poisonous spider. It hurts and leaves a little mark on the skin. It is no big deal. There are none of the serious, protracted symptoms that one would exhibit when bitten by a latrodectus mactans. A latrodectus spider's web is irregular in shape and is made of strong threads. Black widow spider webs appear uneven and tangled. ... Females tend to hang upside down from their webs, allowing the red, hourglass marking on their abdomens to become visible. This marking signals danger to predators and other attackers.