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A commercial colony ofBombus terrestris(L.) was introduced to Japan in 1992 for crop pollination in greenhouses. Since then wild colonies have developed and spread in some regions. In the present study, we measured the spatial distribution and temporal change in abundance ofB. terrestrisin the Chitose River Basin, Hokkaido, Japan to elucidate the relation of greenhouses to the bee’s distribution and to evaluate its potential effects on native bumblebees. Bumblebees were collected with window traps in windbreak forests roughly 1, 2, 4, and 6 km NNW and SSE of a large greenhouse. The peak catch ofB. terrestrisqueens occurred in early June, suggesting that they had successfully hibernated in the field. The distributions ofB. terrestrisand the nativeB. ardenswere mutually exclusive, while the nativeB. hypocritaappeared at all sites. Catches ofB. terrestriswere restricted to within 4 km of the nearest greenhouse, suggesting that the invasion was still in the initial phase in this area. The reduction in abundance of the native bumblebees in the sites of highB. terrestrisabundance suggests the presence of interspecies competition betweenB. terrestrisand the native bumblebees during the early part of the colony activity, although such reduction inB. ardenscan be explained by habitat suitability. [ABSTRACT FROM AUTHOR]