dominated by oaks. The species is also one of 11 non-native bees in the U.S. state of Hawaii. Humans are thought to have helped the species colonize Pacific archipelagoes. It is not known when X. sonorina was introduced to the Hawaiian Islands, but it occurred prior to 1874, when British entomologist Frederick Smith originally named the species, and X. sonorina is currently found on all of the main Hawaiian Islands and in the Mariana Islands. In tropical agriculture, X. sonorina has been used as a pollinator of Passiflora edulis, a species of passion fruit. Located in the Pacific Ocean, more than away from the closest landfall in North America, Hawaii's great distance from the Americas is thought to have been too large for natural biological dispersal to succeed, and it has been suggested that it is likely humans aided X. sonorina in its arrival to Hawaii. Following the colonization of Hawaii, X. sonorina was introduced into the Marianas Islands, China, and Japan, but these introductions were not successful. The species has also been anecdotally reported in Midway Atoll, Java, New Guinea, and the Philippines, but only the records from Midway have any specimens recorded that serve to confirm the report. Only two other species in the genus Xylocopa have successfully colonized Pacific archipelagoes east of the Americas through natural biological dispersal or with human help; This is out of a total of more than 150 identified species in North and South America, 70 of which can be found in Brazil alone. The two species are Xylocopa darwini, found in the Galápagos Islands, west of South America, with the mainland of Ecuador as the closest land mass; and Xylocopa clarionensis, found on Clarión Island in the Revillagigedo Islands, from the coast of Mexico. X. clarionensis is thought to be most closely related to Xylocopa sonorina. Life cycle In the spring, females mate with males and then may disperse and start new nests, or clean out and enlarge the old tunnels used during the winter, adding brood cells. Each cell a female provisions contains a substance called "bee bread", which is a mixture of pollen and nectar used as food for the larvae. An egg is deposited on the pollen mass and each cell is sealed off with a partition of sawdust. Young adult male and female bees hibernate in the tunnels during the winter. Behavior Female behavior Virgin females may make