That is EXACTLY what they are.... and they do eat tarantulas. They are so FAST, LOL, good to know they're docile an I've never been approached by one directly, but they are pretty scary and fast movers, too... I got stung once by something on the ear, and that was immensely painful. It was probably just a regular bee since the stinger lodged itself in my ear, but something about being stung on the head... I ran through my office towards the first aid kit, screaming, everyone was making fun of me, and I've been stung plenty before, but something about the head area? I was nauseous and dizzy and my ear swelled to boxer size, honestly, I almost left early for the day. I don't mind bee stings usually but this was... unfortunate. If those wasps have one of the most painful stings in the world, I don't want to find out. 
Anna
Anna