Big as mice. He would wait for the door to open and run for cover. We tested this. It was like having a small rat in the garage. Bug bombs do not kill tarantulas.
Bug bombs kill their food.
Then they leave. One year my eldest got down and worked with one of these migrating creatures until he could pet it. Another year we caught one and took it to the back bank. I was running thru the yard in my nightgown - and ran into spider webs. Big spider webs.