Making a Bee Hotel for Solitary Bees

Why Solitary Bees Deserve a Hotel

Of the roughly 270 bee species recorded in Britain, the vast majority are solitary. They do not live in colonies with a queen and workers, and they do not make honey. Instead, each female works alone, building a nest of several cells, stocking each one with pollen and nectar, laying an egg, and sealing it up. There is no hive to defend and no swarm to worry about, which makes them wonderfully safe neighbours in a small garden.

Around a quarter of our solitary bees nest in hollow plant stems or in tunnels they find in dead wood. In a tidy garden, that kind of nesting habitat is often the first thing to disappear. A well-made bee hotel gives these bees somewhere to raise the next generation, and it costs very little to put together. Get the details right, though, because a badly designed hotel can do more harm than good.

Choosing the Right Spot

Placement matters as much as construction. Solitary bees are cold-blooded and need warmth to become active, so a south or south-east facing aspect is ideal. The nest should catch the morning sun, which gets the bees going early, and be sheltered from the prevailing wind.

A few practical rules will keep your hotel working well:

• Fix it at least a metre off the ground, ideally between 1m and 2m, where it is out of reach of damp soil and most ground predators.
• Give it a roof overhang so rain cannot blow straight into the tunnels. Dryness is essential — damp tubes grow mould and kill the developing larvae.
• Mount it on a wall, fence or post that stays firm. A wobbling hotel puts females off, and they will simply nest elsewhere.
• Keep it away from bird feeders and dense shrubbery where tits and other birds can ambush bees as they emerge.
• Avoid full shade and anywhere that stays wet, such as under a dripping gutter or beside a pond edge.

Building the Hotel Body

Use untreated timber. Pressure-treated or tanalised wood contains preservatives that are not kind to insects, and varnishes and paints can seal the surface in ways that affect moisture. Offcuts of oak, beech or any hardwood work beautifully; softwood is fine too, but it wears faster around the tunnel entrances.

Drill holes into the face of a block, working with the grain where you can, and make sure every tunnel is blind-ended — never drill right through. A female needs a sealed back wall to build against. Depth of around 10cm to 15cm suits most species, and the entrance should be clean and splinter-free. A light rub with sandpaper removes the fuzz that can tear delicate wings.

Space the holes roughly 15mm to 20mm apart so neighbouring bees are not disturbed by each other's comings and goings. A block about 20cm square and 15cm deep makes a generous, manageable unit, and you can stack several blocks into a frame to make a larger hotel.

Tubes, Sizes and Which Bees They Attract

Cardboard tubes and cut bamboo canes are the other half of a good hotel, and they have the advantage of being replaceable. For bamboo, choose canes with intact nodes and cut them just beyond the node so each piece has a natural sealed end. Paper or cardboard tubes are even better, because you can slide them out and swap them entirely.

Variety is the key to a busy hotel. Different species need different tunnel widths:

• 3mm to 5mm: the smaller mining and yellow-faced bees, which are easily overlooked but excellent pollinators of fruit and herbs.
• 6mm to 8mm: leafcutter bees, which line their cells with neat discs of rose and birch leaf.
• 8mm to 10mm: red mason bees, the familiar spring nesters that plug their tunnels with reddish mud.
• Larger holes tend to be ignored, or worse, used by solitary wasps. Anything above about 12mm is usually wasted space.

Mix the sizes in one hotel and you will attract several species across the season, from the first mason bees in March through to leafcutters in midsummer.

Keeping It Clean and Healthy

This is the part most people miss, and it is the difference between a hotel that supports bees for years and one that quietly becomes a reservoir of disease. Over time, tunnels accumulate pollen debris, dead larvae, mould and parasites such as pollen mites and the ruby-tailed wasp, which lays its eggs in other bees' nests.

Replace the tubes every year or every other year. Wait until the bees have emerged — usually late spring for mason bees, late summer for leafcutters — then gently remove the old tubes, brush out the block with a dry bottle brush, and fit fresh ones. If you find cocoons still inside, handle them carefully and store them somewhere cool and dry until spring.

Never use pesticides, cleaning sprays or soapy water inside the hotel. Dry brushing is enough. If a block becomes stained or crumbly, it is time to drill a new one.

Planting for the Bees Nearby

A hotel is only half the story. Solitary bees need a steady supply of flowers within a few hundred metres, so treat the planting around it as part of the project. Spring nesters rely on early sources such as willow, hawthorn, apple blossom and lungwort, while summer species need knapweed, viper's bugloss, borage, comfrey, lavender, oregano and sedum.

Allow a little wildness — a patch of long grass, some dandelions left to flower, a log pile — and your bee hotel will become part of a genuinely working habitat rather than a lonely ornament. Watch the tunnels through spring, and you will soon see neat mud plugs and leafy caps appear, each one a small, solitary success.