Анотація:
The males of E. najas are waiting for females sitting on the leaves of water lilies. This peculiarity of the behaviour permits presenting the damselflies with plane surfaces and geometric figures for settling. The painted surfaces were ranged according to decreasing attractiveness as follows: yellow, orange, white, green, azure, blue, black. Presumably the choice of the colour is ruled by the relation: maximum of long-wave rays-minimum of short-wave rays. The figures with convex edges were more attractive than dentated ones. Stochastic patterns with different statistical parameters were equally attractive.