Artificial nests really do work for solitary bees and are easy to make. The simplest option is to drill holes into some old dry wood, or bundle some bamboo or hollow plant stems together and put them in an old bit of pipe to keep them dry. Different species of bees use different sized holes, so the holes that you drill should have a range of diameters from 2 to 10 mm, but no bigger. Many ready-made bee homes have holes that are much too large and will never be used. The holes should be drilled about 8 to 15 cm deep.
You could try making a solitary bee home out of transparent tubes. Bundle them together and put them in an old plant pot so that the tubes are in darkness. Then at the end of the season you could take a tube out and see the amazing nests left behind by the bees. Just make sure to put the tubes back again after you've had a look.
The best place to hang a bee home is on a south-facing wall, between 30 and 100 cm above the ground and in full sun. Suspend the bee home with a slight tilt, so that rain cannot enter the open holes. If you are using a pipe that is open at both ends, then hang with one end of the pipe against the wall. Sites sheltered from the wind are best.
We suggest you put your bee home up in March or early April. This will offer prime nesting sites for solitary bees laying their eggs. You can tell when nests have been built as you will see the ends of the bamboos sealed with mud or leaves.
In autumn you might need to take down the bee home to protect it from winter wet. The artificial nest must be put somewhere cold but sheltered, such as a unheated shed, carport or garage. If the nest gets too warm the bees will wake up much too early and die of cold and hunger, and if it gets too wet the mud walls of the cells can dissolve and the young bee larvae will become infected with fungus diseases. Remember to put the nest back outside again in March so that the adult bees can emerge at the correct time.
It is important to clean or replace artificial nesting tubes regularly to prevent the spread of pests and diseases. It can be best to have multiple small nest blocks or stem bundles, which will naturally deteriorate over time, and add fresh new nests to the garden each year or two.