Abstract: The development of Callosobruchus maculatus F. on five grain legumes-Calopogonium mucunoides Desv., Centrosema pubescens Benth, Desmodium intortium (Mill) Urb., Flemingo congesta (Vestita Benth ex Barker) and Pureria phaseoloides (Roxb) Benth used as cover crops in Oil-Palm Plantations in Nigeria was studied under laboratory conditions. Vigna unguiculata L. Walp seed was used as control. Each of the six leguminous seeds was infested with five males and five females of C. maculatus. The treatments were arranged on a laboratory bench in Complete Randomised Design (CRD). V. unguiculata had the highest geometric mean diameter of 78.85 mm and 1000 seed mass of 283.33 g, followed by C. pubscens with 3.35 mm and 33.33�4.71 g seed mass. Eggs were laid on five of the species except D. intortium and the number increased with increase in seed size. The number of eggs laid was significant (p = 0.05) and ranged from 123.2 in V. unguiculata, F. congesta 63.5 and C. mucunoides 36.7, C. pubesens 18.2 and P. phaseoloides 17.2. Although development was complete in F. congesta, only miniature adults measuring 2.6 mm were produced while C. maculatus adults on V. unguiculata measured 3.9 mm. Development from egg to adult took 25�2 days in V. unguiculata and 33�1.5 days in F. congesta while it did not go beyond the third larval instar in P. phaseoloides. For management of C. maculatus, C. mucunoides, C. pubescens, D. intortium and P. phaseoloides are recommended for use as cover crops since they are not alternative host plants of C. maculatus.