Insects that undergo complete metamorphosis, such as Drosophila,have two waves of neurogenesis. The embryonic wave, which generates the neurons that regulate larval behaviour, has been extensively studied. However,little is known about the postembryonic patterning of the adult-specific structures of the central nervous system (CNS). On p. 5167, Truman and colleagues use mosaic analysis with a repressible cell marker (MARCM) to follow adult-specific lineages of cells produced from individual neuroblasts in the ventral CNS of larval Drosophila. They identify the 24 lineages that make up the scaffold of a thoracic hemineuromere, and show that the adult-specific cells in a given lineage are all very similar and project to only one or two initial targets. The description of these initial contacts provides a developmental framework for future studies into how the complex connectivity of the adult CNS is achieved.