Enhancer trap lines have been used to generate a collection of molecular lineage markers specific for different subsets of glia in the Drosophila embryo. Using these markers, we have been able to describe the diversity and pattern of glia along the major axon pathways in the embryonic central and peripheral nervous system. Just as these and other studies show the great diversity of embryonic glia, so too the enhancer trap lines described here point to a remarkable degree of molecular heterogeneity, and probably a concomitant functional specificity, of the embryonic glia.