Pollen host spectra of the ten Central European Hylaeus species classified as oligolectic. x-axis: Plant families: ADO = Adoxaceae, AMA = Amaryllidaceae, API = Apiaceae, ARA = Araliaceae, AST = Asteraceae, BOR = Boraginaceae, BRA = Brassicaceae, CAM = Campanulaceae), CAR = Caryophyllaceae, CIS = Cistaceae, CRA = Crassulaceae, ERI = Ericaceae, EUP = Euphorbiaceae, FAB = Fabaceae, FAG = Fagaceae, GEN = Gentianaceae, HYP = Hypericaceae, LAM = Lamiaceae, LYT = Lythraceae, ORO = Orobanchaceae, ORO/PLA = Euphrasia, Rhinanthus or Veronica, PLA = Plantaginaceae, POL = Polygonaceae, RAN = Ranunculaceae, RES = Resedaceae, RHA = Rhamnaceae, ROS = Rosaceae, RUB = Rubiaceae, SAX = Saxifragaceae, SCR = Scrophulariaceae, TIL = Tiliaceae, VIT = Vitaceae, ? = unknown pollen types. y-axis: Percentage of pollen volume contained in the female crops.