The suspect was arrested later at his home.
Police say the 18-year-old woman was in her apartment Tuesday about 2 p.m. when she heard a knock on her bedroom door. Authorities say the man, who did not have permission to be in her apartment, grabbed the woman and tried to rape her.
The woman's dog, a pit bull, started acting aggressively, and the man fled.
Thirty-year-old James B. Benson Jr. of Dover was arrested Wednesday and charged with attempted rape and other offenses. He is being held after failing to post $51,500 bail.