The Dialogue Pages

Blue banded bees

When people start to talk about native bees, they most commonly say that they have seen blue banded bees in their garden. Because they are quite a large, noisy bee, about 15 mm long, they are easily seen and heard while they flit from flower to flower (Figure 1). These bees are beautiful creatures, with bands of colourful hairs on their abdomens. Although they are known as ‘blue banded’, the bees in the genus Amegilla can have bands that range from vivid blue through to greenish, pinky–red or white.

Figure 1: Blue banded bee, displaying pale blue bands of hair on the abdomen, alighting on a salvia flower.

Species that occur in the Sydney region are Amegilla pulchra and Amegilla asserta, and it is not easy to separate them from each other. The species shown here is A. asserta and the male and female can be distinguished from each other by their facial markings. The female has darker features on her face (Figure 1) and also has dark markings on her hind tibia (leg) (Figure 2 & Figure 3).

Figure 2 Amegilla asserta female showing dark facial markings and reddish facial hair.
Figure 3 Amegilla asserta female, showing dark marking on hind tibia (back leg).
Figure 4 Amegilla asserta male, showing smaller hind tibia without dark marking.

The male has very bright yellow markings on his face (Figure 4) and is smaller than the female (unfortunately I didn't have the grid paper when I was photographing these bees) and has finer legs (Figure 5 & Figure 6).

Figure 5 Amegilla asserta male, showing bright yellow facial markings compared to the female.
Figure 6 Amegilla asserta male, showing finer legs and smaller stature.
Figure 7 Amegilla asserta female, showing dark facial markings and more robust stature as well as red colouring of the thoracic hairs.

Compared to A. pulchra, the facial colour is usually more yellow in A. asserta and the facial and thoracic hair is redder.

However, the colour ranges can overlap and that is why it is so difficult to separate them. An expert, like Michael Batley, may be able to separate the females of A. pulchra and A. asserta by the white patch on the tip of the abdomen (T6), but only if the specimen is in good condition. So if you can get a good image of the tip of the abdomen, which may help to clarify the species. Unfortunately I was unaware of this when I took photos of this specimen, so the tip of the abdomen isn't well visualised. Maybe next season.

Blue banded bees like to make short burrows in clay–type soils. They will nest in creek banks, mud bricks and old mortar and prefer to nest in areas near other bees of the same species. This is known as nesting in ‘aggregations’ and it helps to reduce individual predation as there is safety in numbers. These bees can be encouraged to nest in your garden. Rammed earth bricks can be constructed and placed in a sunny position, but with some protection from the weather. It may take some time (two seasons) for the bees to take up residence but patience is usually rewarding (Figure 8 & Figure 9).

To make “rammed earth” blocks for Blue Banded Bees, you will need AT LEAST three large Besser blocks. This species likes to nest in aggregations so you need to give them enough nesting material to create an aggregation. I used eight blocks for my “wall” at home. A natural soil mix is best. You should be able to make a “sausage” of moist soil in your fist and it will hold together. But you also need to be able to break the “sausage” easily when you push on it. The clay will hold the shape but the sand will allow them to burrow into the earth. If it is not possible to obtain natural clay / sandy loam soil for the project, you can make up a moist (not wet) mix of premixed “sand and cement” plus “brickies sand” (1:1.5 ratio). Don't put too much cement in or it will set too hard for the bees to burrow into.

Lay the blocks, face up, on some paper to stop the mix falling out. In stages, pack the mix tightly into the bricks with a thick stick or the like. You can put 1cm deep “starter” holes in the soft mix with a pencil if you like. Let the bricks set and then arrange them in a sunny spot. If you can provide them with a “roof” all the better, but not necessary. Place them somewhere you can enjoy them. Uptake by bees is not guaranteed, it's worth trying. I have had successful uptake in my garden.

Figure 8 Blue banded bee inspecting the entrance of a rammed earth nesting block.
Figure 9 Blue banded bee entering the rammed earth nesting block.