Experts in the field often say that spider identification is tricky since very many species resemble each other, and the venomous and the non-venomous ones are found in a complex who's who relationship. Presently, there are all sorts of devices that allow people to catch and analyze the spiders that live in their homes so as to find out whether they are poisonous or not. 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. 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. Relatively smaller than the females, the male spiders of certain exotic species are indeed sacrificed for the perpetuation of their breed. Nevertheless, this is not a general rule as in most cases, both males and females survive the encounter. Not all spider bites are dangerous, since the majority of spider species are totally harmless for humans; with the exception of a few venomous ones, the rest are pretty safe. When a spider bites you, the first thing to do is trying to identify the species, if it be possible; knowing what type of spider bit you may be crucial in case an anti-venom has to be used. The physical reactions to a spider bite are usually classified into local and systemic; the former can be treated at home right after the occurrence of the accident, whereas the latter often require professional medical treatment in order to reduce the reaction of the body to the venom. The local symptoms associated with a spider bite include pain, itching, redness and even swelling of the area; their intensity can be reduced if a tight bandage is applied above the wound. The female black widow spider is more venomous than the male, and it is she the biggest threat to predators. Nevertheless, the red color helps the males too in order to send the same threatening message as the female. While the males move freely in their habitat, the females usually spend their entire lives in just one place, as they very seldom leave their nests.