Solitary mining bees

Female solitary bees make their nests in a variety of places, such as hollow plant stems or tunnels in the ground. About two-thirds of solitary bees are mining bees, who make their nests in little tunnels that they excavate in soft soil. The Steeple Woodlands reserve has a number of soft, sandy paths, Cornish hedges and earth banks that solitary mining bees love to burrow into. Many of these features are a result of the mining that once took place in the area.

The nests often have small piles of mined debris around their entrances. As with all wildlife, please respect the bees and their nests if you come across them on the Reserve.

In late spring or early summer, a young female solitary bee will start looking for a suitable place to make her nest. Once she has chosen somewhere, she gathers some pollen, makes it into a little ball with nectar, and places it at the end of the tube. She then lays an egg onto the pollen-ball, and seals the tube with mud or bits of leaf, before repeating the whole process a little further up the tube. Female leaf-cutter bees will also line the tube with pieces of leaf. Eventually the tube contains a series of cells, each containing an egg and a ball of pollen. Once the female has completed her task and has laid something like twenty to thirty eggs over a period of a few days in one or two tunnels, she abandons the nest to its own devices, and dies soon after.

After a week or so, the eggs hatch and the grubs live off the pollen, before eventually pupating several weeks later. The pupae remain in the nest-tube for nearly a year, only emerging in the following late spring or early summer. When the female bee established the nest and laid the eggs, she cleverly arranged it so that the eggs she laid at the bottom of the tube would become females, while the eggs laid nearer the entrance of the tube would become males. The male pupae hatch first, and are waiting, ready to mate with the females when they appear a little later. The male bees die shortly after mating. The newly mated females then go on to establish new nests, either in the tubes or tunnels where they themselves were born, or in new ones. They too will die soon after.

If you want to encourage solitary bees into your garden, you can make what is known as a ‘bee hotel’. This can be simply a bundle of bamboo canes, about 15 to 18 centimetres long, with the pith hollowed out but leaving one end closed, and hung in a south-facing position where it can catch the sun. Search for ‘bee hotel’ on the Internet and you will find many articles and pictures on how to make and look after a bee hotel.

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A section through a solitary bee nest.
A section through a solitary bee nest showing the balls of pollen, the eggs and the mud walls between the individual cells.
Making a bee hotel.
Making a simple ‘bee hotel’.