Oogenesis in R. prolixus females is induced by feeding blood, blood plasma, a suspension of washed erythrocytes, or 5% solutions of egg albumin, bovine serum albumin or hemoglobin. Unfed females and those fed saline, casein hydrolysate, dextran or sucrose do not initiate oogenesis. The juvenile hormone analogue epoxygeranylgeraniol methyl ester induced oogenesis in unfed females as well as in ethoxyprecocene II-treated insects. The results show that a protein meal was sufficient to initiate oogenesis. They also support the view that oogenesis depends on a relationship between protein ingestion and corpus allatum function and that oogenesis is not controlled by hormones released in response to abdominal stretching.