Motoneuron development is not affected by beat-Iatric-1. Cells of the Bolwig's organs (BOs) form in homozygous embryos, but the morphology of the larval visual system (LVS) is severely disrupted and increased numbers of photoreceptor cells are apparent from the earliest stages of LVS development. Extra photoreceptor cells are seen both in the normal location of the BO clusters and dispersed between the two clusters. Embryos sometimes contain three BO's and, rarely, four BO clusters are seen. Migration of the BOs appears relatively normal in some embryos, but in others it is disrupted and the BO does not achieve its proper location even though head involution appears normal, or the BO is elongated. Larval visual system development occurs normally in 93% of beat-Iatric-1 embryos expressing beat-IaScer\UAS.cFa under the control of Scer\GAL4bi-omb-Gal4. However, a large number of these embryos fail to develop.
In a subset of embryos three distinct Bolwig's organs are seen.