Imagine what it must be like to be a solitary bee. That perfect hollow stem or old beetle boring you’ve taken ages to find and worn yourself out provisioning before laying your eggs in it may well end up in pieces at the bottom of a compost heap, or chopped up in a shredder or thrown on the fire. Life would be so much easier if you could use a bee hotel.
Bee hotels are on sale everywhere now, marketed as safe, accessible nesting sites for solitary bees in the bee-friendly garden. Many gardeners know very little about this group of bees, and possibly, like me, didn’t even know they existed until the day I saw a small bee resting on a post holding a tiny piece of leaf under her tummy.
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The life of solitary bees
So let me introduce you to the world of the solitary bee. There are some 220 species of solitary bee in Britain, most of which are adapted to specific habitats. They gather pollen and nectar just as honey and bumblebees do, but their nests aren’t a great jumble of activity where the queen is surrounded and helped by her offspring. Instead – and this is what makes them ‘solitary’ – each female does all the work herself, making nests for young she will never live to see.
She lays them out as a series of incubation chambers, sealed off from the next, each one provisioned with a ball of protein-rich pollen moistened with nectar onto which she lays a single egg.
Depending on the species, the chambers are either partitioned with mud, or enclosed in a waterproof membrane or capsule of overlapping leaves. When she reaches the end of the row, she seals the entrance with a thick plug of soil, mud or leaves and moves on to start a new one.
Once she’s exhausted her supply of 15 to 20 fertilised eggs, her task is done and she will die from exhaustion. The eggs meanwhile, nourished by their pollen ball, will develop into larvae, pupate and emerge from their cocoons the following spring or summer.
If you have planted lots of flowers for honey and bumblebees, you will almost certainly have solitary bees in your garden too, but you may not have noticed them because they are so small.
Red mason bee
Bees you're likely to see
The first visitor to arrive in your bee hotel will likely be the red mason bee (Osmia bicornis), on the wing by mid April and a formidable pollinator of fruit blossom. She uses moist soil to partition and plug her nests.
In early summer, leafcutter bees (Megachile species) will bring small fragments of leaves and petals to fashion nests that are shaped and layered like miniature cigars.
Red mason and leafcutter bees are the most prolific users of bee hotels, but you never know who else might turn up. You may also get small solitary wasps nesting in your hotel who patrol your garden hunting for aphids, caterpillars or flies, which they use instead of pollen to feed to their young.
The downside of bee hotels
Unfortunately, bee hotels aren’t quite the paradise for bees that manufacturers would have us believe, as I found out when I opened mine in the early winter of the first year I put them up, to discover that tiny parasitic wasps had worked their way through all my leafcutter bee nests, and destroyed the lot.
Like any artificially created environment – a honeybee hive, for example – bee hotels need to be managed. Concentrating so many nesting tubes in a small area offers rich pickings for opportunists and, big or small, they all come marching in. If you do nothing, parasites will build up and within three years, your bee hotel may no longer be viable for bees.
It may also attract the ‘wrong’ sort of bee. Most species of solitary bee have a dedicated ‘cuckoo’ bee that hangs around outside the bee hotel, and waits – not very subtly – for the rightful mother to leave her nest so she can quickly crawl in and lay her own egg in the as yet unsealed chamber. The cuckoo bee’s egg will hatch more quickly, and her larva will either kill the original larva or starve it by gobbling up all the pollen.
Solitary wasps too have their own ‘cuckoo’ wasps, such as the tiny brilliantly coloured jewel wasp.
The energy and care the little solitary bees put into making their nests and the small dramas of disputes, mating attempts and usurpation that unfold before your eyes are riveting to watch. And, as the hours pass, not much gardening gets done.
The best bee hotels
The best bee hotels are the ones you can dismantle, inspect and clean, just as you would your bird feeders. The ones you can’t open to see what’s going on, should be disposed of after two years and replaced. Protect hotels with chicken wire to prevent woodpeckers, blue tits and other birds from pecking out the bee larvae.
To reduce pest damage use insect barrier glue to seal all the nooks and crannies in your bee hotel. Covering the hotel with layers of duct tape when the bees have finished nesting will also help.
Systems you can dismantle
Nurturing Nature Solitary Bee Observation Nest Box has two observation panels, £70.00 (nurturing-nature.co.uk)
Wildlife World Solitary Bee Hive, £27.99 (wildlifeworld.co.uk)
Systems with cardboard tubes you can replace every year
Mason Bee Nest from CJ Wildlife with 29 cardboard tubes, £10.95; Bee Nesting Cylinder with 32 tubes, £8.95; 20 replacement tubes, £5.50 (birdfood.co.uk)
Kinsman Solitary Bee Nester with 63 cardboard tubes, £14.95 (arkwildlife.co.uk)
Everything you could possibly want to know about solitary bees in the UK is on the Bees, Wasps and Ants Recording Society website (bwars.com). You can also contribute to their recording schemes.
Find out more about the wildlife in your garden