That is a young Black Ratsnake, a harmless and very common snake in the eastern US.
In fact, your glue trap may just have killed the best mouse control you could have had in your attic. While that snake is totally harmless and presents no danger to you or your family members and pets, it would probably catch and eat at least 1 mouse a week and it would be better at finding them than a glue trap.
Take out the glue traps, remove areas where the mice are feeding and hiding, and leave the snakes to do the rest for you. You won't even notice they are there (as was the case prior to the glue trap).
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Chris Harrison
San Antonio, Texas