Aspect mining tries to identify crosscutting concerns in existing systems and thus supports the adaption to an aspect-oriented design. This paper describes an automatic static aspect mining approach, where the control flow graphs of a program are investigated for recurring execution patterns based on different constraints, such as the requirement that the patterns have to exist in different calling contexts. A case study done with the implemented tool shows that most discovered crosscutting candidates are instances of crosscutting delegation and should not be refactored into aspects.