Surface glia consist of two distinct subtypes, the perineurial and subperineurial glia. Perineurial glia are narrow, oblong cells that make up the outermost covering of the adult CNS (Awasaki et al., 2008). During development, these cells increase their cell division to maintain complete coverage of the adult Drosophila nervous system (Avet-Rochex et al., 2012). The function of this glial cell subtype in the adult fly brain remains largely unknown (Edwards and Meinertzhagen, 2010), but a recent study suggests that perineurial glia may be important in the transport of trehalose (the main energy supplying carbohydrate in insects) across the blood-brain barrier (Volkenhoff et al., 2015). Subperineurial glia are large, flat polyploidal cells (Unhavaithaya and Orr-Weaver, 2012) that reside just underneath the perineurial glia layer. Unlike perineurial glia, subperineurial glia undergo endoreplication during larval development to increase their cell size to maintain coverage of the brain through metamorphosis (Unhavaithaya and Orr-Weaver, 2012). These cells contain several tight septate junctions, form the blood-brain barrier of Drosophila, and separate the CNS from pathogens, xenobiotics, and the high electrolyte content of the hemolymph ultimately protecting neuronal function (Limmer et al., 2014; Weiler et al., 2017). Consistent with these functions, the transcriptome of surface glia is enriched for gene categories associated with drug metabolism, cell adhesion, and various transporters (DeSalvo et al., 2014).