orchid bees

The female orchid bees Eulaema meriana visits the male at his lek

Eulaema meriana is a species of large-bodied bee in the tribe Euglossini, the orchid bees. It is a solitary bee and is native to tropical Central and South America. The male collects fragrances from orchid flowers which it stores in hollows in its hind legs. It is territorial and has a particular perch on a tree trunk where it displays to attract a female. After mating, the female builds a nest with urn-shaped cells made with mud, and provisions these with nectar and pollen before laying an egg in each.

Males of this species are territorial and operate a lek system. Each selects a perch on the trunk of a tree at the edge of a temporary clearing in the forest caused by a fallen tree. It chooses a site a few metres off the ground on a tree about 25 cm (10 in) in diameter with smooth, bare bark. Here it stands in a characteristic pose with its head close to the bark, its front and hind legs extended and its middle legs folded underneath its body. Periodically it “buzzes”, vibrating its wings while opening and closing them to display the yellow abdominal markings. At intervals it takes off and flies a few metres away from the perch before looping back to land close to its previous spot. The same perches are used by males every day, both in the morning and in the afternoon, but are unoccupied for a period in the middle of the day. In ensuing years, the same spots are used again as long as the clearing in the forest still exists.

Females have large ranges in which they forage and these may contain a number of different male territories, some solitary and others in loose groups. A female attracted to a territory circles around with the male before landing on the perch tree, often taking off again and then settling several times. When the male is successful in landing on the female’s back, the mating process lasts for about five minutes, after which time the female flies off. It is not apparent what part the fragrances collected by the male and stored in the hollow in his hind legs play or how they may facilitate the breeding process.

After mating, a female usually chooses a cavity as its nesting site. If the entrance is too large, a mud wall may first be built in which a hole about 1.5 cm (0.6 in) in diameter is made. The mud is gathered in small balls by the mandibles, transferred progressively to the fore, mid and hind legs, and deposited in the pollen basket on the hind leg. About six balls make a load, three in each basket and the female flies back to the nest site. Inside the cavity, a pedicel is constructed on which an urn-shaped cell is built. The mud of which it is made hardens as it dries. The outside of the cell is usually covered by a thin layer of faeces brought in by the female and the inside is lined with resin which is drawn up to form a flexible collar at the top. Each brood cell is provisioned with a cream-coloured mass made from a mixture of pollen and nectar, tamped down and filling two thirds of the cell. On about the fourth day after the construction was started, an egg is laid in the cell and the female folds in the collar and caps the cell with mud. The pedicel is extended and further cells are built against the long wall of the first giving a group of neatly arranged cells. The construction and provisioning of the later cells occupies less time.

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