Published online by Cambridge University Press: 31 May 2012
Records on Megachile centuncularis (Linn.) were obtained in connection with research on pollination of alfalfa in Wisconsin. At no time abundant, specimens were collected while tripping alfalfa flowers in Bayfield, Brown and Dane Counties. One bee tripped 95 per cent of the alfalfa flowers visitedand the earliest record was June 9th in Dane Co. Other flower records included fireweed, Epilobium angustifoliurn L., and goldenrod, Solidago sp. In Ontario, Pengelly (1953) found a female on sow thistle at Guelph, and observed a few specimens on alfalfa at Cayuga; alfalfa flowers were visited at the rate of 26-28 per minute and tripping efficiency was 99-100 per cent. Mitchell (1935) listed flower records that indicated a generalized habit, but the bee showed preference for composites