Building a Simple Bee Hotel for Solitary Bees

Why Solitary Bees Need a Hand

Solitary bees are the quiet workhorses of the British garden. Unlike honeybees, they do not live in colonies, build hives or produce honey. Each female works entirely alone, laying her eggs in her own small nest, and most of our roughly 250 native species nest either in the ground or in hollow plant stems and old beetle borings in dead wood.

Those nesting places have become harder to find. Tidy borders, strimmed verges, dead wood cleared away for safety and neatness, and plastic-free gardens that are nonetheless stripped of hollow stems all remove opportunities. A bee hotel is not a substitute for flowers, and it will not fix a shortage of forage, but it offers solitary bees somewhere safe and dry to raise the next generation. It is cheap, it takes an afternoon, and it works remarkably well in a small garden, courtyard or even on a balcony.

Choosing the Perfect Spot

Where you hang the hotel matters as much as how you build it. Solitary bees are cold-blooded and need warmth to become active, so choose the sunniest, most sheltered wall or fence you have. A south or south-east facing aspect is ideal, because the morning sun will warm the structure and get the bees flying early.

Aim to mount it roughly one to one and a half metres above the ground, fixed firmly so it does not sway or rattle. Tuck it under a slight overhang, such as a shed eave or a fence rail with a small roof, so driving rain cannot soak into the tubes. Avoid spots that stay damp, sit in all-day shade, or catch the prevailing wind. Keep it away from bird feeders and dense shrubs where tits and other birds can perch and pick off emerging bees. Ideally, place it within a few metres of flowers and a patch of damp, bare soil, since many mason bees use mud to seal their nests.

Building the Hotel: Bamboo or Drilled Wood

Two materials do most of the work, and both are simple to prepare.

• Hollow bamboo canes: cut them into lengths of 15 to 20 centimetres, cutting just below a node at one end so that end is naturally sealed. The open end faces outwards. A mix of diameters between 3 and 10 millimetres suits different species, though most garden visitors prefer 6 to 10 millimetres. Smooth every cut edge with sandpaper or a sharp knife, as rough fibres tear delicate wings.
• Drilled wooden blocks: use untreated hardwood such as oak, ash or beech. Softwood splits and splinters. Drill holes 6 to 10 millimetres wide and 10 to 15 centimetres deep, never drilling right through, with holes spaced about 15 to 20 millimetres apart centre to centre. Sand the entrance holes smooth and brush out all dust.

Bundle canes tightly inside a tin can, a length of drainpipe or a wooden frame, packing the gaps so nothing shifts. Give any block a back board and a small overhanging roof. The bees will do the rest, lining each tube with mud or neatly cut leaves and packing it with pollen and nectar before laying a single egg.

Common Mistakes to Avoid

A few easy errors can turn a well-meant hotel into a death trap.

• Holes that are too wide or too shallow, which leave the brood exposed or produce mostly male bees.
• Splintered or rough entrance holes that damage wings.
• Plastic straws, glass tubes or drinking straws, which trap condensation and encourage mould.
• Painted, varnished or chemically treated timber, and any timber treatment inside the holes.
• Pesticides nearby. Do not spray insecticides on flowers, aphids or nest sites within reach of the hotel, and leave the aphids for ladybirds and blue tits instead.
• Moving or cleaning the hotel between March and September, while it is in use.
• Hanging it in shade or in a spot where water collects.

Solitary bees are gentle and rarely sting, so a hotel close to a path or a child's play area is perfectly safe, provided it is out of the way of knocks.

Keeping It Clean and Ticking Over

Clean the structure gently once a year, in late winter or very early spring, after the bees have emerged and before new ones arrive. Take the canes and blocks out and brush them with a soft dry brush or paintbrush. Never soak them in water and never use cleaning products. Replace bamboo canes every year or two, as they degrade and can harbour mites and mould. Drilled blocks last far longer and can simply be brushed out and reused.

If you find cocoons while cleaning, handle them as little as possible and leave them somewhere sheltered outdoors rather than bringing them indoors; the bees need natural temperatures to develop properly. A well-sited hotel is usually around half to three-quarters full, so if every tube is packed, hang a second one nearby.

What You Might See in Spring

The first red mason bees usually appear in March and April, with males emerging a little ahead of the females and hovering impatiently around the nest entrances. Leafcutter bees follow in early summer, and you may spot the neat semicircular notches they snip from rose and lilac leaves. Each female will fill around ten to twenty tubes over the season, working steadily from morning until the warmth fades.

Be patient if nothing arrives in the first year. It can take a season or two for word to get around, but once a hotel is discovered it tends to be used year after year. Pair it with a few lavender, borage, comfrey or foxglove plants nearby, keep the soil undisturbed, and you will have created a small but genuinely useful piece of spring habitat.