(A) Under ordinary conditions, wild-type Caenorhabditis elegans embryos hatch into larvae. (B) We targeted maternally-expressed genes by RNAi to induce embryonic lethality that varied in penetrance across strains. (C) L1 larvae in the parental generation were fed Escherichia coli expressing dsRNA against target genes, in 96-well plates in liquid media. 5 days later, wells were imaged to capture the penetrance of embryonic lethality in the next generation. (D, E) Raw images were evaluated using DevStaR (White et al., 2013), which identified objects as larvae (blue), dead embryos (green), or adults (red).