Observations on Phacelia tanacetifolia Bentham (Hydrophyllaceae) as a food plant for honey bees and bumble bees

Published source details Williams I.H. & Christian D.G. (1991) Observations on Phacelia tanacetifolia Bentham (Hydrophyllaceae) as a food plant for honey bees and bumble bees. Journal of Apicultural Research, 30, 3-12.
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This study is summarised as evidence for the following.

	Action	Category
	Plant dedicated floral resources on farmland Action Link
	Plant nectar flower mixture/wildflower strips Action Link

Plant dedicated floral resources on farmland

Williams & Christian (1991) planted three 9 m² plots of phacelia at Rothamsted Research experimental farm, Hertfordshire, England. Seven species of bumblebee, including the long-tongued common carder bee Bombus pascuorum, and one cuckoo bumblebee B. [Psithyrus] vestalis foraged on the phacelia. Of observed worker bumblebee visits, 97% were for nectar, not pollen.
Plant nectar flower mixture/wildflower strips

A replicated study in 1989 in Hertfordshire, UK (Williams & Christian 1991) found that seven species of bumblebee Bombus spp., including the long-tongued common carder bee B. pascuorum, and one cuckoo bumblebee B. [Psithyrus] vestalis foraged on plots sown with phacelia Phacelia tanacetifolia. Of observed worker bumblebee visits, 97% were for nectar, not pollen. The plots each flowered for six to eight weeks, with a maximum flower density of more than 4,000 flowers/m² on the plot sown in late May. The plot sown in July flowered until early December. Three 9 m² plots of phacelia were sown at Rothamsted Research experimental farm in May and July 1989. Bee and flower densities were recorded weekly. Flowers were counted in a 0.25 m² area of each plot. Bees were counted at 09:00, 11.00, 13.00 and 15.00 in each plot, their behaviour, species and gender were recorded.