I used to think the reason we see a lot of dead bugs wrapped and hanging on spider webs was that they get caught by spiders and after the spiders are done with the bugs they leave them there. But I have had a few spiders trapped in a plastic bottle and that assumption no longer seems correct. I haven't found any articles online that sufficiently address this.
I notice that the spiders in the bottle actually actively work to make web to hang up dead bodies, even if the bodies are much larger than them in size and are not their prey. For instance, there was a pretty sizeable spider in the bottle when I trapped a few newcomers. The large spider had been dead in there for weeks. I was just too lazy to get its body out. The newcomer spiders were much smaller but they soon worked to wrap up the dead body of the large spider and hoist it so it didn't stay at the bottom. The same also happened with the body of a moth several times their size. House spiders in general don't attack other bugs that outsize them or even their own size because they only attack bugs they can pin down. So the moth died of natural causes in the bottle-starvation I assume, but its body was also hoisted. Why do they do that?