Detailed studies on the immature stages of the sorghum head bugs, Eurystylus immaculatus Odhiambo and Creontiades pallidus Rambur, were carried out in the laboratory at Samanko, Mali, during November 1991 to March 1992, and January to April 1993, and in the field in October 1993. Eggs of both species were laid in maturing sorghum (Sorghum bicolor) grains. The egg incubation period was 4–7 days in E. immaculatus, and 5–7 days in C. pallidus. There were five nymphal instars in both species. The total nymphal period was 6–11 days in E. immaculatus and 8–14 days in C. pallidus. The durations of first, second, third, fourth and fifth nymphal instars were 1–3, 1–2, 1–2, 1–3 and 1–3 days, respectively, in E. immaculatus, and 1–3, 1–2, 1–3, 2–3 and 2–4 days, respectively, in C. pallidus. All the immature stages of E. immaculatus are described and sketched.