(101 is a topic for beginners in any area. It has all the basic principles and concepts that are expected in a particular field)

The Black Widow 101

Black Widow Family History

Male is likely to be killed by the female after the coupling, or sometimes even before intercourse has been initiated. How ever, male can sometimes even live in the web of a female for a while without being harmed in any way. 
Although the male may sometimes die during mating without the female actually consuming him, this species represents a possible strategy of "male sacrifice". Males that "sacrifice" themselves gain the benefit of increasing their paternity relative to males who do not get cannibalized.
This sacrifice of male mates might occur despite the obvious disadvantage to the sacrificial males. One theory is that once the male has mated, he is unlikely to mate again and so any further extension of his life is of lesser evolutionary benefit. This scenario would be consistent with a hypothesis that old or unfit males get eaten, whilst younger and fitter ones may survive to mate again.