Homozygous blw^KG05893 mutants are smaller than controls (at the same stage), with the majority dying at the second instar larval stage, with 20-30% of larvae reaching the third instar. Examination of the fat body in third instar larvae reveals a dramatic reduction in thickness and a significant reduction in the ratio of triglyceride-to-protein content. Overall mitochondrial number is not affected in these mutants. Staining with Mitotracker suggests functional defects in these mitochondria. These mitochondria also exhibit alterations in diameter and length compared to controls.