An EMS mutagenesis screen was conducted in Drosophila melanogaster to identify growth control mutants. The multi-institution Fly-CURE consortium phenotypically characterized the O.2.2 mutant using the FLP/FRT system which displayed a mutant lethal phenotype with reduced head development, and darkened ocular tissue. Complementation mapping was conducted to identify the affected gene. A failure to complement was identified in Uba3 , resulting in the identification of the novel allele, Uba3 O.2.2 . Uba3 is a known disruptor of the cell cycle and our data are consistent with early larval/embryonic lethality displayed in numerous species.