Required for the establishment of stable connections between the larval optic nerves, the Bolwig's nerves, and their target cells in the brain during embryonic development. Expressed at low levels in the adult head and very low, but detectable, levels in the body. Expression is seen as early as 6 hours of embryonic development and continues throughout embryonic and larval stages, increasing in abundance at each larval molt. The level remains high during pupal life but decreases to low levels in the adult.