Where did snug as a bug in a rug come from?

The phrase "snug as a bug in a rug" first appeared in the 18th century, with the meaning of being warm and comfortable. It is believed to have originated from the idea that bugs (i.e., insects) are cozy and content in the protected environment of a rug. Over time, the phrase has come to be used more broadly to describe feeling comfortable, secure, and snug in any situation.