To study the relations between flowers of Nymphaeaceae and insects investigations have been carried out in two Dutch waters viz. the ”Oude Waal” near Nijmegen, where Nymphaea alba L. occurs, and the ”Haarsteegse Wiel” near Vlijmen where Nymphaea candida Presl occurs, while Nuphar lutea i(L.) present in both waters. The flowers of these Nymphaeaceae are attractive to certain insect species in their search for food, which is provided directly by the soft parts of the flower, stigmatic exudate, pollen and nectar or indirectly as prey in the form of other animals present in the flower. By this behaviour of the insects pollination is favoured, The flowers of Nymphaea candida are not really suitable for insect pollination as they are often half-submerged. Consequently very few seeds per fruit have been found in comparison with Nymphaea alba.