Love1 is calling in the temperate forests of Australasia. An exotic perfume (called a pheromone) floats in the air, sending an irresistible message to the males of just one species of insect—the Fungus Gnat—that a female Fungus Gnat is nearby and desires a mate.2 A male gnat answering the call finds that the amorous female appears to be located within the flower of a Greenhood Orchid.3

When a male gnat lands on a protruding part of the flower called the irritable lip or labellum, the lip, which is hinged, suddenly snaps shut, imprisoning the gnat within the flower. Is the gnat about to become the orchid’s breakfast? No, the Greenhood Orchid has a much more sophisticated use for the gnat.

As the gnat explores his tiny prison, he notices light coming in from a ‘window’ above him. Could it be an exit?

As the gnat crawls up to investigate, he has to squeeze along a narrow tunnel lined with hairs. In doing so, he brushes against two strategically placed parts of the flower. The first exudes a sticky liquid, and from it he receives a dab of glue on his body; the second provides a parcel of pollen which adheres to the glue as he moves forward. Ahead is an exit, and the gnat makes it out into the world again, but now carrying the Greenhood Orchid’s means of reproduction.

The orchid takes from 30 minutes to an hour to reset the lip, thereby providing the means whereby another gnat will enter the flower.

Love frustrated, the male gnat flies off in search of romance and is soon lured again by the fragrance of another Greenhood Orchid. It seems he has not learned his lesson and the call of love is too strong. This time he will fertilize the other orchid with the pollen he is carrying on his back. The orchids also have their stigma (the ‘female’ part in plants that receives the pollen) strategically placed in the path of the gnat, ready for a ‘loaded’ one….

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