Ensheathing glial cells are closely associated with neuronal arborizations and synaptic regions. We determined that these cells express PER in the central brain in Drosophila. It has been reported that the equivalent mammalian cells, the microglia express Per1 and Per2 in a circadian manner (Hayashi et al., 2013; Fonken et al., 2015). The ensheathing glia of Drosophila uniquely express key components of the glial phagocytic machinery such as the engulfment receptor Draper (Doherty et al., 2009). Interestingly, a recent study comparing circadian transcriptome in heads of young and old flies indicated that drpr mRNA show a rhythmic profile in young flies but the rhythm is dampened in old (Kuintzle et al., 2017).