Ethylene oxide fumigation reduced the content of histidine in stored dandelion pollen and of histidine and methionine in rape pollen.Apis melliferaL. colonies reared fewer larvae than control colonies when fed fumigated pollen. Ethylene oxide fumigation also destroyed some unidentified lipid attractants contained in pollen. Foraging bees collected less, and bees in the hive consumed less fumigated pollen than unfumigated pollen.