Adding a dye, Calco Oil Red N-1700, to the larval diet of Chilo partellus has been shown to be a useful method for marking the moths for mark and recapture experiments. The method is time-saving and the dye is safe to handle; marked insects and their egg batches are easy to detect. Insects reared on dyed diet did not show any differences in development time or pupal weight compared with insects reared on normal diet.