The paper reviews the work done on the population patterns of Chilo spp. in relation to the phenological stages of sorghum, maize and millets. The stem borer Chilo partellus entered sorghum and maize crops at 2–3 weeks after emergence and continued till harvest. There were 3–4 peaks of larval population during a cropping season. Such studies not only reveal the relationship between the larval population density and the phenological stage of the plants at infestation time, but are also helpful in scheduling and timing pest management strategies.