Spiders are notoriously antisocial, with a number of species known for making a meal out of recent mates. But there are some notable exceptions to that rule, called the social spiders. These can form groups of thousands of spiders, which cooperate to capture prey and build nests that can grow up to six meters long. Their group construction projects allow them to hunt prey that is much larger than any of them could capture individually.

For one species, Anelosimus eximius, however, these big nests appear to come with big risks. Some population surveys indicate that over 20 percent of nests end up going extinct each generation. And, since only mature females that have already mated can successfully start up new nests, this means that most of the spiders in the nest end up dying.

Now, researchers from the University of British Columbia have proposed an explanation for the population busts. It seems that the spiders are a bit too good at sharing, so that even weak and immature colony members are generally able to get something to eat. And, if food ever gets a bit short in the nest, that means that none of the spiders may get enough food to survive.