Hemilineage 1A is composed of cholinergic interneurons and has been shown to be implicated in erratic forward locomotion (Lacin et al., 2019; Harris et al., 2015). Muscle-specific homeobox (msh) was shown to be the hemilineage-specifc transcription factor expressed in the mature 1A cluster (Lacin et al. 2019; Lacin & Truman, 2016). The 1A hemilineage cluster projects through the ventral anterior commissure and then, after reaching the midline, forms  a ‘hook’ which splits at the tip, creating dorsal and ventrolateral projections. The arbors of the ventrolateral projection terminate in the leg neuropil, while the arbors of the dorsal projections terminate in the tectulum (Harris et al., 2015).