<p>Neuronal remodeling is essential for the precise formation of mature nervous systems. <i>Drosophila</i> serves to study neuronal remodeling; however, existing experimental systems are insufficient for examining circuit-level neuronal remodeling and its effect on behavior. We present a new model system to investigate neuronal remodeling. We show that the Moonwalker SEZ neuron, which elicits backward walking in adult flies, is part of a conserved circuit persisting from larva to adult. Utilizing the system, we examine developmental neuronal remodeling, describe a gene-regulatory mechanism controlling outgrowth, and uncover a causal relation between remodeling and behavior. The well-characterized connectivity of the circuit, low number of elements, direct control of the motor output, and availability of specific driver lines, provide an appealing system to study developmental remodeling of neuronal circuits and their impact on behavior. Hence, we establish a new model system in <i>Drosophila</i> to investigate neural circuit remodeling and its relation to behavior.</p>