The spatial distribution of plant pests within crops is often heterogeneous, at least during some growth periods. Within-field heterogeneity implies that plants at some sites may need pest control while plants at other sites do not. Automated detection, identification and quantification of diseases and invertebrate pests on a small scale are the prerequisites for a site-specific pest management strategy. This chapter reviews how sensor technologies in combination with informatics and modern application technologies may enable pest control where and when it is actually needed. We summarize and discuss the potential of aerial and proximal remote sensing using various types of sensors for applications ranging from quarantine, to the production of speciality crops, to crop loss assessment.