Leafcutter bees do what their name suggests in that they cut holes and semi-circles out of leaves, to line their nest. The nest is in the ground, under stones, in cavities in wood and stone, pithy plant stems, and in dead wood. The egg is laid in a cell under the ground, in which food has been placed. The cell is then sealed as part of a series of closely packed cells so that a finished nest tunnel may contain a dozen or more cells forming a tube 10cm to 20cm long. Adult females only live up to about two months and lay between 35 and 40 eggs. When the new adult bees are ready to emerge they eat their way through the leaf. The last egg laid is the first to hatch and are usually males, they hang around on nearby flowers waiting for the females to emerge.
Mining bees, or digger bees, nest in burrows in the ground. Each mining bee female usually digs her own individual burrow to rear her own young. Large numbers of these bees may nest near one another if soil conditions are suitable.
Mining bees are not aggressive and seldom, if ever, sting. The presence of numerous bees flying close to the ground, however, may constitute a nuisance for some people. Sometimes large numbers of males will fly about the same spot for several days in a mating display.
Mining bee burrows may be located wherever there is exposed soil and good drainage. They are frequently found nesting in banks, such as along road cuts or any type of excavation, but may also be in level ground as well. The holes are about 6 mm (1/4 inch) or less in diameter. They are sometimes surrounded by a small mound of soil that the bee has brought up to the surface. Burrow structure varies according to species, but often there is a vertical tunnel with smaller side tunnels that terminate in a single cell.
The female mining bee stocks each cell with pollen and nectar she collects from flowers and then deposits an egg on the food mass. The larva hatches and consumes the stored pollen and nectar. When mature, it becomes a pupa, or resting stage, and finally becomes an adult bee. The adult bees overwinter below ground in the burrow site. During the next spring or early summer the adults emerge, mate, and the females begin burrow excavation. Mining bee populations can fluctuate dramatically from one season to the next.
Wool carder bees
The wool carder bee Anthidium Manicatum is also one of the most exciting and interesting insects you could be lucky enough to witness! The male Wool Carder Bee sets up a territory around one or two patches of flowers. He patrols these flowers and deals very aggressively with any insect that strays into the patch. He darts at an intruding insect to chase it off.
The bee is named after the female’s habit of scraping the hairs off plants, rather like carding wool. She uses the hairs to line a cavity in a wall, in timber or any other suitable place. The hairs are gathered together into a ball. She flies off carrying the ball of wool, which is sometimes as big as her! If you can watch the females ‘carding’ plant hairs, you may be lucky enough to witness one fly off with its cargo of ‘wool’ – it really is a fascinating sight.
Hairy leaved plants like Lamb’s Ear or Lychnis coronaria are important for this purpose. Back at it’s cavity nest, the female provisions cells with pollen collected from plants guarded by the male. She then lays eggs in the cells which develop into larvae that feed on the pollen provided by the ‘mother’. The following season, in June and July, new males emerge, followed soon after by females, and the whole cycle starts again.
Female carpenter bees dig tunnels in dead wood where they lay their eggs. Carpenter bees can be considered as pests by some because of their wood boring habits; however they rarely do any serious damage, drilling into the surface of wood only.
Like the leaf cutter and mason bee, adults spend the winter in nests constructed the previous year, and become active in April or May. After mating, females construct new nesting tunnels or use pre-existing tunnels. Nesting tunnels are about 12mm wide and start on the end of wooden beams or at right angles to a surface for 10mm to 25mm before turning and following the wood grain. Tunnels are clean cut and may extend 15cm to 20cm. Females collect pollen and nectar to produce a dough-like mass called “bee bread.” The eggs hatch into larvae that feed on the bee bread in their cells.
In the UK there are 6 species of cuckoo bumblebees. These were once themselves like other bumblebees, but they have switched to a parasitic existence. The females are especially powerful, and force their way into the nests of their bumblebee hosts. They kill or evict the queen and take over her workers as their own, using them to rear their own offspring.
Cuckoo bumblebees do not produce workers of their own. Each cuckoo species tends to attack a particular species of bumblebee, so for example the southern cuckoo bumblebee targets buff-tailed bumblebee nests.