The spatial and temporal distribution of the European red mite Panonychus ulmi (Koch) on mature grapevines (Vitis vinifera L.) was studied during the different phenological stages of the plants. P. ulmi showed circadian movements between the lower and upper surface of the leaf: in the morning, the mites were located preferably on the lower surface. When the sun illuminated the leaf, particularly in warm weather, clear sky and in the absence of wind, they moved to the upper surface of the leaf. In the evening they returned to the lower surface. The spider mites were not homogeneously distributed among the main shoot leaves, but showed preferences for certain leaves, which varied with the phenological stage of the host plant. At the beginning of the vegetation period, when the main leaves were still growing, the younger leaves were not infested and the mites concentrated preferably on the oldest ones. When the main leaves were fully grown, the mites lodged preferably in the middle of the shoot. The distribution of the spider mites on the entire plant (double Guyot training system) also varied according to the phenological stage of the grapevine. At the beginning of the growing season 60% of the entire mite population was located on the first three shoots on each side of the trunk suggesting that the head of the trunk must be a preferential oviposition site. After bloom they were homogeneously spread over the vine. The density of the mite population on the lateral leaves was closely correlated with the density of the mite population on the main leaves. The European red mite showed a clear feeding preference for the main leaves.