A guy finds a hole in his wall, and behind it, a strange leathery brown mass. He pulls it out -- first mistake. He cuts it open -- second mistake. Within…
It's a wasp nest stuffed full of dead spiders, each with an egg planted in them. It's just adorable. There are more photos. I was kind and picked the least horrific.
Good odds that those spiders are not dead, merely comatose. The wasp wants them to stay alive enough to guarantee that their flesh is still fresh and delicious when the wasp larvae are ready to eat.
When in grad school I used to look at the nests of these critters for a now-forgotten project. Anyway the wasps that built the nests I was looking at in Northern Indiana collected crab spiders pretty much exclusively. Which I should think would be particularly difficult and dangerous as the spiders are ambush predators.