At this meeting, we can all agree that the chemical senses are endlessly fascinating in their own right. However, they also provide a powerful entry point for a range of strategies to study the neural circuit basis of behaviour. Two examples of this are the close association between olfaction and memory in many species and the processing of pheromones to control sexually dimorphic behaviour. Another theme of growing importance in neuroscience is the use of synaptic resolution brain wiring diagrams (connectomes) in order to reveal circuit logic. I will discuss examples from our own work in Drosophila that apply experimental and connectomics approaches to olfaction to reveal general principles of sensory processing and behaviour.