The acute temperature dependence of many biological processes, including neuronal excitability, have been described. But much less is known about how the nervous system responds to long-term changes in temperature. As a grass fellow I will manipulate temperature during the development of Drosophila melanogaster, which is likely to be a critical period for the establishment of a neuron’s molecular and functional identity, and investigate the resulting effects on motoneuron excitability, robustness to acute temperature change, and transcriptome. I will then repeat these experiments in progeny from mothers undergoing reproductive diapause, a naturalistic response to extreme temperature. These experiments will help to explain the basic but elusive question of how set-point excitability is established during development, and how a simple environmental perturbation affects the development and function of the nervous system.