Dendritic Pruning During metamorphosis, Drosophila sensory neurons eliminate their dendritic trees, but axons and soma remain intact. Kanamori et al. (p. 1475 , published online 30 May) demonstrate that compartmentalized calcium transients in dendrites function as the spatiotemporal cue for pruning of unwanted branches. Such a localized calcium signal, induced by a local elevation of branch excitability, activates calcium-dependent proteinases and eventually causes branch death.