One of the insects that feeds on pedunculate oak acorns and reduces its seed yield is Curculio elephas Gyll. The study of Curculio elephas Gyll is necessary because of the severe damages caused by this insect and also owing to its insufficiently investigated biology. The research was conducted in the common oak seed orchard at Banov Brod, forest estate Sremska Mitrovica“, and in the entomological laboratory. The adults emerge from the soil chambers from mid July till the beginning of September. The presence of adults, as determined by crown fogging, ranged from the end of July till the beginning of September with the highest number in mid August. After emerging from the soil, females are already fertile with the developed eggs in the ovaries. They start egg laying after 1 to 8 days and they lay from one to seven eggs per day. Egg laying period lasts from 7 to 20 days. Fertility of C. elephas females ranges from 5 to 40 eggs, while their fecundity ranges from 19 to 45 eggs. At the end of the larval stage, larvae bore into the soil and stay there from one to three years. The species hibernates only in the larval stage. C. elephas has a one-year life cycle, while a minor part of the population has a two or three-year life cycle.