Cyclocephala lunulata is a frequent scarab species in Colombian agroecosystems, but its biology is widely unknown. Aiming to describe the immature stages and to study some biological aspects related to its life cycle, distribution and agricultural importance, parents of the species were collected from two dry tropical forest areas [Palmira and El Cerrito, in the Colombian Cauca-Valley (800-1000 mm/year)] and confined in vessels with fruits and organically enriched soil. The larvae are distinguished, due to the maxilla with 3 terminal unci, the smaller medial one with free apex, the maxillary stridulatory area conformed by 7 small truncated teeth and a thicker distal one; the species is widely distributed from 0 to 1700 m.a.s.l., predominating on warm lowland below 500 m.a.s.l. The larvae were located in the ground at depths between 3-15 cm, and they more abundant after rainy seasons. They feed on decomposed plant debris; the life cycle was semestral (150-180 days), with very short larval stages II and III, as well as a short reproduction period (15-20 days). An identification key based on morphological diagnostic characters of the larvae is presented. The larvae are discarded as rhizophagous pests, and it is associated to organic matter and soil formation processes, whilst the adult is just a secondary pest on some fruit tree species like guava (Psidium guajaba). The study and the protection of the larvae populations in soil are recommended.