Robbing of Exotic Plants by Introduced Carpenter and Honey Bees in Hawaii, with Comparative Notes

In Hawaii, a carpenter bee (Xylocopa sonorina) and the honey bee (Apis mellifera) use floral perforations to obtain nectar. With its maxillae, X. sonorina perforates corollas and calyces of introduced plant species; in corollas of different lengths and diameters, the perforations made are significantly different in length. Through these perforations, X. sonorina imbibes nectar without pollinating the flowers. Old and New World Xylocopa spp. perforate the flowers of at least 22 families. Apis mellifera obtains nectar through perforations made by X . sonorina. Elsewhere in the world, A. mellifera uses previously made perforations in flowers to obtain nectar from at least 10 plant families. These bees are "robbers" of some plants in that they take floral provisions in ways that are unlikely to effect pollination.