Visualization has long been accepted as a viable means to comprehend large amounts of information. Especially in the context of software evolution a well-designed visualization is crucial to be able to cope with the sheer data that needs to be analyzed. Many approaches have been investigated to visualize evolving systems, but most of them focus on structural data and are useful to answer questions about the structural evolution of a system. In this paper we consider an often neglected type of information, namely the one provided by bug tracking systems, which store data about the problems that various people, from developers to end users, detected and reported. We first briefly introduce the context by reporting on the particularities of the present data, and then propose two visualizations to render bugs as first-level entities.