In most insects, the initial phase of embryogenesis involves multiple nuclear divisions to generate a syncytium, migration of the resulting nuclei to the cell cortex, followed by cellularisation. This last process has been thoroughly studied in Drosophila: the plasma membrane invaginates around the nuclei and extends to generate a basal membrane, forming a layer of epithelial cells. To what extent is this process conserved in other insects? To investigate this (see p. 2173), Maurijn van der Zee and colleagues studied cellularisation in Tribolium castaneum, a beetle that has more ancestral traits than Drosophila. Among other differences, the authors found previously undescribed junctions linking the extending basal membrane to the forming yolk membrane. To identify the nature of these junctions, they performed a parental RNAi screen and found that the disruption of Innexin7a (Inx7a), whose Drosophila orthologue is dispensable for cellularisation, significantly impairs basal cell closure during Tribolium castaneum cellularisation. Inx7a is localised at the basal membrane of the forming epithelium and is required for its formation and for the stabilisation of the invaginated membrane. This study provides insight into the mechanisms of cellularisation in a non-Drosophila insect model, which are likely to be conserved in a greater number of insects.