Even in North America there are three different types of the black widow spider and their classification is made according to the geographical area where they live: there is the northern black widow, the southern black widow and the western black widow; thus the species is widely spread from the south of Canada to Mexico. When you are able to identify spider species correctly, the risk of getting bitten out of personal negligence is a lot lower; moreover, in case you do get bitten, you can provide valuable information about the species, thus making treatment a lot easier. Many patients are yearly treated for the wrong affection because of the misidentification and misdiagnoses of spider bites. You should be concerned when the symptoms do no improve within 24 hours and there is numbness or increase in pain. The greatest risk of a spider bite is anaphylaxis: the allergic reaction to spider venom that is sometimes encountered with very sensitive people. Hives, wheezing, shortness of breath and weakness are the general symptoms associated with anaphylaxis, therefore call 911 right away if you notice any such symptoms. The severest form that a brown recluse spider bite can get is that of necrosis when the deep tissues are affected and get gangrenous; the venom actually destroys the soft tissue, the area heals very slowly and scarring is inevitable. A brown recluse spider bite gets painful and itchy within two up to eight hours from the incident. Poisonous Spiders Many people have a phobia when it comes to spiders; hairy legs, devious traps, innocent victims : this is the picture that they usually imagine. This unjust pattern is not justified since even the most poisonous spiders will not attack a human unless they felt threatened. All spiders need to inject venom in order to survive, it is in the nature of their species and one of the life mechanisms they have been endowed with; what really differs from one species to another and gives rise to the classification into poisonous and non-poisonous is the amount of venom and its toxicity. The great thing about these creatures is that they have adapted to the harshest of environments from the desert and the tropics to the Arctic areas where they can live underwater. In terms of gender relationships, male spiders are famous for being killed right after intercourse, or at least this is the general myth people know.