Dawson's Burrowing Bee (Amegilla dawsoni)
Article | Updated 5 years ago
This is one of the largest and handsomest of Australia's native bees, only some carpenter bees (Xylocopa spp.) being larger. It is a solitary, ground-nesting species and females burrow into bare clay flats to make their nests. Like many other 'solitary' bees, Dawson's Bee exhibits gregarious tendencies and females usually nest in close proximity to one another. An active nesting colony may contain up to 10,000 burrows and can provide one of the most exciting entomological experiences.
The species is confined to Western Australia and inhabits the plains of the north-west and extends south to near Paynes Find. Adults occur only during the months of July to September when their forage plants, poverty bush (Eremophila spp.) and Rough Bluebell (Trichodesma zeylanicum), are in bloom. For most of the remainder of the year the species exists as dormant larvae in underground brood cells.
While females shelter in their burrows overnight, males roost on vegetation, gripping leaf tips or stems in their jaws and folding their legs beneath their bodies.
At the bottom of the shaft at depths of 15-30 cm, the female constructs an urn-shaped brood cell and waterproofs its walls with secreted wax. By means of several foraging trips, she half-fills the cell with nectar and pollen (the pollen settling to the bottom), then lays an egg on the surface of the nectar. Finally, she caps the cell and then commences to construct another slightly deeper. She may repeat this process up to seven times before filling in the shaft, sealing it with a mud plug and demolishing the turret. Exhausted by her labours, she may then die on the ground. The eggs hatch within a few days and the tiny larvae commence swallowing the liquid food in which they float. They grow rapidly and consume all their provisions within a few weeks. At this stage they are bloated white grubs nearly filling the cells. Then they pass faecal material which is smeared around the cell walls. When this process is completed they curl up and remain motionless and unresponsive until the following year. Transformation into a pupa and then an adult occurs still within the sealed cell. The young adults have to gnaw their way through the cell cap and burrow to the surface.