Brown recluse and black widows are not acceptable to have in the house. If you see one, kill it. You cannot afford to be bitten by one. Few others in the States are quite as scary as those. Unless the wolf spider is very large, I would leave them alone. They don't hurt anything except other creepy-crawlies.

I know of no tarantulas that can jump very high and have never heard of any that would jump at a person. Spiders don't attack anything bigger than they are--that's suicide. They have a very good sense of self-preservation. I could make mine beg. They do rear up in a defensive posture if you dangle something above them because they think it's a pepsis wasp. So you dangle something and say, "Up, up, up!" and it looks like it's begging. Old trick--like a flea circus.

The coolest spiders I've ever heard of are these little red ones that live on the floor of the desert--don't remember which one. The desert floor is pitted with holes and the spider find the right sized hole to use as a burrow.

It can't spin a web outside the hole because the winds blow the sands over the floor and will tear a web to pieces in no time. So that the spiders do is gather little pieces of quartz that are all over the place and place them in a ring around the hole. They are careful to make sure all the crystals touch.

Then they attach a thread to one crystal, drop it into the hole and then attach the other end to the crystal on the opposite side forming a little sling. Then they sit in it like the man on the flying trapeze. When a bug wanders too close, the spiders can feel the vibrations in the crystals and dart out of the hole and grab the critter and haul back down and eat it.

The spiders know the difference between the wind causing the crystals to vibrate and an insect or some other animal. They know how big the creature is, they know where it is around the hole and how far away from the hole it is. It never attacks something too big and never misses when it knabs a bug--that's how exact its knowledge is.

But how do these spiders know that crystals vibrate and can function as a makeshift web? How do they know that the crystals have to be touching in order to conduct the vibration? How do they get such an accurate read on the vibrations?