Stigma Region of a carpel (female productive organ of a flower) that serves as a receptive surface for pollen grains and on which they germinate.

Tracheal mite Acarapis woodi, parasite of honey bees, accidentally introduced into the United States that has caused colony mortality in many locations.

Trioecious Staminate, pistillate, and perfect flowers borne on different plants.

Varroa mite Varroa jacobsoni, a parasite, accidentally introduced from Asia that became established in the United States. It continues to cause heavy mortality of bee colonies in some regions. The mite feeds externally on bee larvae and pupae within the brood combs.

Worker One of the thousands of sterile daughters of the queen. Worker ovaries usually are undeveloped. Workers typically work inside and then outside the nest as foragers, living for only 4–6 weeks during the spring and summer months. Bumble bee queens also produce workers, but many fewer than honey bees.

Xenogamy Cross-pollination and cross-fertilization of plants.