“Help, there’s a demented bee following me!” The call was from my wife, at the back door.
“Don’t worry, she’s just a blue-banded bee looking for a place to lay her eggs.”
“Oh…” At which point feminine solidarity kicked in and the bee in question was allowed to continue her search of our bricks without further hindrance.
Blue-banded bees (Amegilla cingulata) are one of the commonest native bees around Sydney, and can be found in most states and PNG. Related species are found in many other parts of the world.
They are solitary bees, though they quite often seem to like nesting or roosting near other bees. They are slightly shorter and stockier than a honey bee, and below is a typical view of a foraging bee approaching rosemary flowers, tongue extended for nectar.
The bright yellow coloration on her back legs is from golden pollen grains held in her pollen basket or scopa (the special hairs for holding pollen on her back pair of legs.) Where the flowers visited have cream or white pollen, or when the bee has recently brushed itself down, the bee looks more like this male (males have 5 bands, females 4.)
Apart from being solitary, blue-banded bees have other behaviours that are quite different from the better-known honey bee. One is their pollen extraction technique. As well as the usual pollen-gathering and nectar-sipping, they practise something called buzz pollination on certain flowers.
Buzz pollination, which is unknown to honey bees, is a more efficient way of getting some flowers to release their pollen. It is employed by blue-banded bees and related species such as the teddy bear bee. Flowers that benefit from buzz pollination reportedly include commercially important plants such as tomatoes, blueberries, egg plants, chillies, and kiwi fruit as well as various native species. In our garden they regularly forage on tomato and basil flowers, but largely ignore the chillies.
To buzz pollinate, the bee flies onto the anthers of the flower and wraps its body firmly around them, holding on tightly with its legs. It then buzzes loudly for a second or two, before releasing the flower. You can see a bee doing exactly this to a tomato flower in the picture below.
Research in 2015 by a team including Drs Katja Hogendoorn of Adelaide University and Sridhar Ravi of RMIT has uncovered more details about the blue-banded bee’s special buzz technique, which differs from that used by bumble-bees, for example.
Apparently the bee is able to switch the powerful muscles in its thorax from its wings to its head. It then uses rapid contractions and relaxations of these muscles (hence the buzz) to bang its head against the flower’s anthers. In this way a blue-banded bee is able to head-butt the anthers a staggering 350 times a second to release the pollen. This requires some of the highest muscle acceleration rates known in the animal kingdom - no wonder you can see slight blurring of the bee’s head in the preceding photograph!
There’s a remarkable slow-motion video of the action by one of the research team, Callin Switzer, on Youtube at https://youtu.be/KBHrNpgNPBo
All bees get covered in a fair amount of pollen, which they have to clean off. Our blue-banded bees get more than most, thanks to their hairy bodies and buzz pollination. As a result they have developed a unique and quite entertaining cleaning technique.
First the bee finds a suitable twig or leaf to land on (chive leaves are a favourite.) Then it latches on to the chive with its powerful mandibles, and lifts the rest of its body off the leaf, so that it is doing a headstand on its jaws. Next, it rapidly combs its head, body, antennae and wings with a series of rapid sweeps of its legs. The hairs on the legs act as fine-tooth combs, with the final sweeps being done by the large hind legs to collect the pollen in the scopa. To reach the various parts of its body, the bee has to swing its body from side to side by swivelling its neck while its head and jaws remain rigidly locked. You can get some idea from this sequence:
And here’s a front view. In this case, the bee’s left antenna is flipping back upwards after being brushed by the front leg now sweeping down its eye:
The overall effect is rather like a furry toy with an attack of St Vitus Dance. The following video is set to half speed, to allow you a slightly better view of what is happening. (Warning - it's about 6Mb so may take a few seconds to download.)
The locked-jaw headstand position is also used by the male bees when sleeping at night (females sleep in their burrows). This bee was by itself, but sometimes they roost in small groups, and may even be joined by other species of bee or a small wasp or two.