Mud dobber type wasps that fly in to my garage in the summers are looking for spiders TO EAT,thats one of their favorite foods. Then later I see other types of spiders eating the wasps that have got in their webs. Natures way of taking care of things.The wasps were attracted to the same plants that the spiders had set up home on. The Garden Spiders wiped out those wasps over two or three weeks time.
And brown recluses are like vultures or cat fish,they eat dead bugs laying around. If you see a trail of dead bug carcasses in a dark musty place like a garage chances are you have some brown recluses there,they feed on the dead bugs and leave their carcasses.
Ive only seen one black widow here since Ive been living in Oklahoma but back home in California where I live I live near a couple of wineries and they are hell'a thick there as theyre drawn to the grapevines. If you see spider webs inside a bunch of grapes that came from Cali a black widow was probably there.