2 things:

1. I wanted to congratulate the writer of the article for noting that in spiders cannibalism is more a case of convenient predation than anything else.

2. It’s never easy to summarize info like this for popular consumption. However, the group known as ’spiders’ is so varied that it’s difficult to create generalization for the entire group (rather like saying all plants have flowers or all birds act like eagles). The truth is there are many types of spiders where cohabitation among adults is the norm. In the Salticidae – or Jumping Spiders – adult males and females of many species regularly share a common retreat made of silk. These individuals will mate, but there is no cannibalism. In communal spiders where dozens – if not hundreds of individuals live together in a massive shared web cohabitation by adults is the norm, not the exception.

So while a female Black Widow ‘can’ eat her mate, it is NOT an obligatory behavioural strategy in this species.

If one wants a ‘good’ story of ‘mating gone bad’, one should take a look at the reproductive behaviours of the Six-spotted Fishing Spider Dolomede triton. In this species the males compete to be the first one to mate with a newly emerged female. The male that mates with a female gets away after mating. However, after mating the behaviour of the female changes. Any male that attempts to court an already mated female is allowed to approach very close. Once he is ‘too close’ the female kills and eats the male. This isn’t ’sexual cannibalism’ (sensu strictu) but it is predation that capitalizes on sexual behaviour. In D. triton the population of adult males crashes as the number of mated females increases… to the point that there are no adult males left at all. Talk about getting even on a gender!