boston terrier, age 18 mos. chews everything, digs holes, won't come to us

Hello-
Our male Boston cannot be left outside of his crate unless he is watched constantly. Even with discipline, his habits continue. He has many chew toys, but it doesn't help. Will this continue into his adulthood?
I also have a pug who is perfect, and our Boston seems to "teach" the pug these bad habits, so I almost hate to put them together, since he is rather corrupting the pug's naturally good behavior. So, the Boston winds up spending most of his time crated. Even if the Boston were our only dog, I still could never trust him on his own, he would destroy our house and yard.
Will this be how he is forever? Our pug has never been in a crate and has never destroyed anything, unless he is with the boston terrier.
Please help, all suggestions welcomed. Cindy