Experiments were made to evaluate the impact of the floral activity of the insect visiting fauna on Cucumeropsis mannii yields. Two lots of 566 female flowers (in 2004) and 759 female flowers (in 2006) were differentiated according to the presence or the absence of protection for insect visits. The foraging entomofauna, the rhythm of insect activity, the fruit set rate and the mean number of seeds per fruit were recorded.Results showed 33 and 29 insect species foraged on C. mannii flowers. Among them, Apis mellifera was prominent. Insects foraged throughout the day light period and during the whole blooming period of the plant. Their activity was highest in the morning hours. During their visits, bees intensively and preferably harvested nectar coming into contact with anther or stigma when foraging. The fruit and seed sets were exclusively effective in unprotected female flowers whereas those of protected female flowers were nulls in both years. Then, the foraging activity of insects mainly bees on C. mannii appears as the limiting factor in the production of this crop. Therefore, the installation of A. mellifera colonies and the conservation of the wild bee nests close to C. mannii field are recommended to maintain and improve yields in the region.