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These are the bees that cut
holes and semi-circles out of rose leaves, and other leaves, to line the cells
in their nest. They nest in a variety of places, in the ground, under stones,
in cavities in wood and stone, pithy plant stems, and in dead wood. In some
countries, the US, France and New Zealand these bees are raised to pollinate
crops.
The female bee places a supply of honey and pollen in the cell; lays an egg on this, then seals the cell and builds the next one in the cylindrical hollow. Once she has sealed the last cell she goes off and dies. When the new adult bees are ready to emerge they eat their way through the leaf parts. The last egg laid is the first to hatch. The last eggs laid are usually males, and they hang around on nearby flowers waiting for the females to emerge.
Megachile centucularis, also known as the upholsterer bee and the rose leaf cutter is on the right, and is found right across Eurasia and North America. In the UK they fly from June to August. The female uses rose, birch, ash and many other leaves as long as they have a serrated edge. The tunnel diameter is 7 -8 mm, and 9 - 12 pieces of leaf are needed for each cell. The cells are thimble shaped inside, and each is sealed with 4 - 12 circular pieces of leaf. There are usually 6 - 10 cells per nest. Each cell takes the bee around 6 - 8 hours of work to construct, provision with honey and pollen and to lay an egg. She does not have pollen baskets but carries pollen back to the nest in the bright orange brushes on the underside of her abdomen.
At night she rests in the nest entrance facing outwards and will bite anything that tries to enter. The eggs hatch in 12 - 16 days, feed then spin their cocoon 17 -18 days later. Fecal pellets help stick the outer layer of the cocoon to the inner leaf layer of the cell.
Sweat bees.
These are in the Halictidae family. Most are small - medium sized, and as with all bees feed on pollen and nectar, however they get their common name from their habit of licking the perspiration off human skin. Most species are solitary, but there are a few social nesting species.
There are some very important differences between the bumblebee life cycle
and the honeybee life cycle. There is no mouth-to-mouth exchange of food
between adult bumblebees, nor do adults groom each other or the queen as is
seen in honeybees. As yet no equivalent to the honeybee "queen substance" has
been found; in honeybee hives workers licking the queen and each other pass the
"queen substance" throughout the hive, and this pheromonal control enables the
queen to maintain dominance. Bumblebee queens appear to maintain dominance
purely by aggressive behaviour.
With bumblebees the colony is
started anew each year with only the new queens surviving the winter. Whereas
the honeybee hive continues year after year, even though there may have been a
change of queens during the summer. During the cold winter months the honey bee
workers cluster around the queen deep in the hive to maintain a high enough
temperature to survive, they also feed on their store of honey. So when the
weather warms enough for them to forage there are already a large number of
workers. Honeybee queens never forage, they live their lives inside the hive
only emerging to found a new colony when they swarm with a full compliment of
workers. Bumblebees in temperate climates never swarm, however there are a few
tropical species that initiate new colonies by swarming. For more on honeybees click here
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Getting drunk and falling down
Coryanthes sp., the south American bucket orchid tree epiphyte opens its flowers in the early morning and drips fluid from two glands into its bucket. The fluid gives off a scent attractive to male bees. The male bees arrive and rub off some waxy substance from the flower. Many male bees are attracted and there is some fighting and pushing, also the aromatic fluid seems to have a slightly intoxicating effect. The upshot of the crowding, excitement and intoxication is that a bee will eventually fall into the bucket of fluid. There is only one way out of the bucket and that is through an escape tunnel. At the exit the tunnel closes, gripping the body of the male bee while gluing two pollen sacs to its back. The bee is trapped for ten minutes, just the amount of time it takes for the glue to dry. When other bees fall into the bucket they are allowed to pass through the tunnel unhindered, but if one is carrying pollen sacs on his back the sacs will be pulled off. This pollination is species specific, i.e. that plant can only be pollinated by a particular species of bee. This is a precarious position to be in if something happens to the pollinator. |