One exit hole is located on either side of the base of the flower. An anther is so positioned beside each exit that a bee of the proper size cannot force its way out without contacting the anther and carrying away a mass of sticky pollen on its back. Since the bee contacts the stigma before the anther and usually does not reverse directions, it does not ordinarily transfer pollen to the stigma of the same flower. Rather, pollination is effected when the bee, upon escaping from the first flower, is subsequently trapped again, usually in a different flower, and the escape procedure is repeated. This strategy is often effective in bringing about cross-fertilization.
Botanists are uncertain just why the bee enters the flower in the first place.
In some cases the entry is inadvertent. The bee, exploring the outer surface of the lip, tumbles into the trap. In other cases entry appears quite deliberate. It has been conjectured that small amounts of nectar are present or that the bees feed on the hairs on the inside of the lip. But it now appears likely that the flower provides no food, and the bee is simply deceived by false nectar guides and the odor of the blossom, which promise nectar where none is available.