The data set contains data on: 1] Prey type and size (sheet1: prey type and size). In the cells, prey length in mm is provided for each prey item. NA is stated for a prey item that could not be measured. In this sheet, the plot ids and the spider ids are also stated, which enables connection with other sheets. Note: more prey items caught by an individual are stated in one row if they are of different type. Prey items of a same type caught by an individual are itemized in more rows. 2] Information about spider individuals (sheet2: spiders). For each spider individual, it is provided its id, so it can be connected with sheet 1, plot id where it was collected, when it was collected (month), web type, and prosoma length (mm). 3] Characteristics of sampling plots (sheet3: environmental data). It is provided plot id, age, infestation degree by Hymenoscyphus fraxineus, canopy openness, shrub coverage, and herb coverage. 4] Potential prey of spiders (sheet 4: potential prey). Standardized no. of prey per trap (20 x 15 cm, both sides were sticky) in each plot.