The process of Arthropod segmentation occurs on a spectrum, with simultaneous segmentation (e.g. Drosophila) at one end and sequential segmentation (e.g. Tribolium) at the other. These two extremes can be explained by two main networks with different timings: one establishes ‘pair rule’ gene expression, which the second network converts into segment boundaries via timer genes. These networks act concurrently in simultaneous segmentation, but asynchronously for sequential segmentation. How do these same genes achieve sequential or simultaneous patterning? Shannon Taylor and Peter Dearden address this question in Nasonia vitripennis (a parasitic wasp that diverged from Drosophila around 300 million years ago) using hybridisation chain reaction, RNA interference and computational modelling. First, they characterise the expression patterns of Nasonia segmentation genes, which are expressed in a similar order to Drosophila. However, unlike Drosophila, anterior pair-rule genes in Nasonia are expressed consecutively, rather than simultaneously (termed ‘progressive segmentation’, which can be explained by timer gene expression dynamics) and posterior pair-rule genes are sequentially expressed. Nasonia appears to have two network modules that regulate pair-rule gene expression, as in Drosophila. Finally, modification of the Drosophila gene regulatory network in silico can reproduce some features of progressive segmentation in Nasonia, indicative of a largely conserved, ancient network.