Rearing trials on several Bombus species were carried out in 1990 and 1991. The purpose was to improve techniques of colony management and to observe colony growth and the behaviour of foraging workers. A total of 5 queens of Bombus hortorum (L.), 32 of B. humilis Ill., 93 of B. lapidarius (L.), 77 of B. pratorum (L.), 5 of B. ruderatus (F.), and 177 of B. terrestris (L.) were collected in spring on flowering plants. No queen of B. hortorum, but 1 of B. humilis, 1 of B. lapidarius, 11 of B. pratorum, 3 of B. ruderatus, and 33 of B. terrestris started to rear larvae, however, workers emerged only in 1 colony of B. lapidarius, 5 of B. pratorum, 2 of B. ruderatus, and 29 of B. terrestris. In 1990, virgin queens and males coming from B. terrestris artificial nests were placed in mating cages; these queens were then used to found new colonies, that were reared throughout the winter until the completion of their cycle.