The Bee Orchid Ophrys apifera flowers in June and July. It is often difficult to find but unmistakable when seen. It is at the northern end of its range, which extends throughout central and southern Europe where it is pollinated by the Longhorn bee Eucera longicornis. The orchid is a sexual mimic – it has the appearance and smell of a female longhorn bee – but in Britain, since this bee is rare, the orchid self-pollinates. The bee orchid is common in southern and eastern Britain on lime.
In the orchid family pollen is transferred to pollinators in packages known as pollinia which stick to the head or proboscis of the bee and are carried whole to another flower. The two yellow pollinia are located just below the green hood and one can be seen in this photo on the end of a long yellow stalk. Darwin was the first to recognise that in Britain self-pollination was almost certain to occur because the stalks that support the pollinia were weak and allowed the pollinia to droop slowly over the sticky stigma below. If a suitable pollinator does not arrive, eventually the pollinia will stick to the female stigma and self-pollination will occur.
The flower of the orchid looks like a female bee and it sends out pheromones that smell like a female bee. When the male lands on what it thinks is the body of the bee the two pollinia (which can be seen just below the green hood) stick to its head and as the bee flies off are carried to another flower.
Since Darwin, considerable research has revealed that not only does the orchid look like a bee, it also emits species-specific pheromones that mimic the female Longhorn bee.