Bee hotel: what it is and how to build one

Let's talk about bee hotels. Have you ever heard of them? Let's find out what they're for and how to build them yourself.

Did you know that there are bees that don't live in colonies and aren't part of a "family"? We've always been accustomed to thinking of bees as social animals, living within highly populated, yet highly organized and quite productive, communities.

Few people know that there are bees that live more solitary lives and are less productive, but this doesn't make them any less important. To protect and safeguard them, humans have built homes specifically for this species.

What are Bee Hotels?

Bee hotels, or pollinating insect shelters, are man-made refuges designed for bees. Just like nesting and wintering sites for pollinators, bee hotels also serve a specific purpose and must be built with specific materials based on the characteristics of the insects in question.

At the basis of these constructions there is the idea that – contrary to what one might imagine – there are not only honey bees that live in colonies, they exist species that prefer a more solitary life without the need to be part of a colony or organized groups.

Suffice it to say that in Italy alone, there are well over 900 species! Even though these bees don't produce hive products, such as honey, their work is nonetheless valuable because, thanks to their characteristics, they are essential to humans and the entire ecosystem. For example, the thick hairs on their abdomens allow them to collect more pollen than honeybees; furthermore, they are more docile and gentle and rarely sting.

The characteristics of a Bee Hotel

Building a bee hotel doesn't require any special skills or a well-equipped laboratory. However, you do need to know... Why We do what we do: every construction choice has a direct impact on the health of the guests who will live there. We're not just hanging a decorative house on the garden wall, we're designing a functional habitat.

The right size for every guest: the diameter of the corridors

The most important detail of a bee hotel isn't aesthetics, but the diameter of the holes. Each species of solitary bee has a different size and prefers passageways proportionate to its body. A hole that's too narrow won't allow the female to enter; one that's too wide exposes her to predators and temperature changes. Precision here isn't a technical quirk: it's the reason a bee hotel works or remains empty forever.

As a practical reference, the most commonly used diameters fall into three bands: very thin holes (2–4 mm) host small solitary species such as Heriades truncorum; medium holes (5–8 mm) are the ones preferred by the’Horned Osmia and many other common mason bees; the larger holes (9–12 mm) can accommodate the Megachile, leaf-cutting bees, and some species of purrbee.

A well-built bee hotel features corridors of several different diameters, not for aesthetic uniformity, but to open the doors to multiple species at the same time.

Depth: Why It Matters More Than You Think

There's a second parameter that's often overlooked, especially in low-quality commercial kits: depth. The passages should be at least 10–15 cm deep, ideally 15–20 cm for larger diameters.

The reason is simple but fundamental: inside each corridor, the larvae overwinter for months. If the hole is shallow, the temperature fluctuations of autumn and winter are transmitted directly to the innermost cells, stressing or killing the larvae. A long corridor, however, creates a natural thermal gradient: the cells closest to the entrance heat and cool more quickly, but those at the back remain in a stable and protected microclimate. It's the same principle as in cellars: the deeper you go, the more constant the temperature.

Additionally, the depth allows the female to deposit multiple eggs in series, usually 6–10 cells per corridor, maximizing the use of space.

Materials to avoid (and why)

Not all materials are suitable, and some can do more harm than good. Chemically treated wood, with paints, stains, or preservatives, releases substances that bees perceive and can interfere with egg laying or even be toxic to larvae. The same goes for plastic: even if perforated, it's not a living material; it doesn't absorb moisture properly and creates condensation inside the passageways. Condensation is the enemy of overwintering larvae: it promotes the growth of mold and bacteria that can destroy an entire generation.

Bamboo canes with internal joints, known as "nodes," are also problematic: the hole isn't dead-end, and the larvae at the node have less protection. Always cut the canes just after a node, so that the bottom is naturally sealed.

Guest Profile: Who lives at the Bee Hotel?

If you've ever heard of bee hotels, you've probably imagined miniature bees flitting in and out of tiny wooden corridors. But here's a distinction that changes everything: the bees that inhabit a bee hotel aren't the same ones that produce the honey in your favorite jar.

The honey bees They are social insects. They live in colonies that can number tens of thousands of individuals, build elaborate hives, and follow a rigid hierarchy, with the queen at the center of everything. We've often talked about them here on Salva le Api, because they are the undisputed protagonists of beekeeping. But the bee hotel is not their home.

The bee hotel is designed for a different, less known and often underestimated world: that of solitary bees.

Solitary bees: numerous, invisible, and indispensable

Over 900 species of wild bees live in Italy. The vast majority are not part of any colony, have no queen to protect, and don't produce appreciable quantities of honey. Each female lives alone, building her own nest, laying her eggs, and then disappearing, leaving her offspring to continue the cycle. It's a life without a court, without workers, without hierarchy. Just her, the nest, and the future she's built.

Among the species that most frequently visit bee hotels in our area we find:

Horned OsmiaKnown as the "mason bee," it is among the first to awaken in spring, often as early as February or March. It has a hairy, rust-colored thorax and a black head, and is an extraordinarily efficient pollinator: just a few individuals are enough to pollinate an entire orchard. It prefers medium-diameter corridors (7–9 mm) and seals its cells with mud.

Megachile centuncularisThis is the famous "leaf-cutting bee." She doesn't use mud to seal her cells: she cuts small circular pieces of leaves (roses, lilacs, birch) and rolls them with pinpoint precision to create capsules in which she lays her eggs. If you've ever found garden leaves with perfectly round holes, it's probably hers. She prefers slightly wider passages, between 6 and 10 mm.

Heriades truncorumSmaller and less conspicuous, it frequents thin corridors (3–5 mm) and uses plant resin to build its cells. It is particularly close to the Asteraceae family, such as daisies and cornflowers.

These species share a fundamental characteristic: they are very active pollinators, often more effective than honeybees on certain plants, precisely because the pollen is not compacted in the "baskets" on their legs but remains loose and abundant on their furry bodies, falling on the flowers at each visit. To learn more about the role of these extraordinary animals, we recommend our article dedicated to Solitary bees and their importance for biodiversity.

Life cycle in the hotel: from the cell to the next spring

To understand how a solitary bee uses the bee hotel is to understand something profoundly beautiful: those silent corridors, seemingly empty for much of the year, are actually full of waiting life.

Spring: the arrival and the laying

With the first warm days, adult females emerge from hibernation and immediately begin searching for a suitable nest. Once they've found the right passageway—the right diameter, sufficient depth, and sunny exposure—the female begins her work with an organization that rivals that of social bees.

First, she collects food: pollen and nectar, which she compacts into a dense pellet at the bottom of the cell. She then lays an egg on top of this food reserve. Finally, she seals the cell with her characteristic material—mud, leaves, or resin—and starts over again for the next cell, working her way outward. In a single passageway, she can lay six to ten eggs, stacked side by side like tiny time capsules.

An interesting note: the eggs laid further down the corridor will be female, while those towards the exit will be male. Males will emerge first in the spring, ready to await the females. This is no coincidence: it's a highly sophisticated evolutionary strategy.

Summer and Autumn: Silent Development

After a few weeks, the egg hatches. The larva finds the pollen and nectar supply left by its mother before it and begins to feed on it slowly over the course of the summer. From the outside, the bee hotel appears motionless. Inside, however, everything is happening.

Towards the end of summer, the larva has used up its reserves and is ready for metamorphosis: it pupates inside the cell, exactly like a butterfly in a cocoon. If you're curious about this type of transformation, we've explained the butterfly life cycle with the same amazement with which we look at bees.

Winter: hibernation

The adult is formed, but it doesn't emerge. It waits. Inside the corridor, protected by the sealed cell, the bee spends the winter in diapause, a sort of controlled hibernation in which the metabolism slows dramatically and the insect withstands the cold without expending energy. This is why the bee hotel shouldn't be moved, overturned, or dismantled during the cold months: entire lives hibernate inside.

Next spring: the circle closes

With the return of warmer weather, the adults gnaw through the cell seal and emerge. Males emerge first, followed by females. They mate, the females seek a nest, and the cycle begins again. The same structure that housed them could accommodate the next generation, year after year, if maintained in good condition.

It's an extraordinarily autonomous and silent cycle. Solitary bees don't require daily care, they don't need to be fed or supervised. They just need a safe space to live, and we can provide it.

To understand how fragile this balance is and why the decline of wild bees is one of the most underestimated environmental emergencies of our time, we invite you to read our in-depth analysis. And if you want to discover all the pollinating insects that share this essential role Along with solitary bees, there's much more to explore in our magazine.

How to build a Bee Hotel?

Building a bee hotel is not only a fun and educational activity, but it also provides essential shelter for solitary bees. Follow this detailed, sectional guide to build your own bee hotel.

How to Build a Bee Hotel: Materials Needed

• Vase: A 12cm tall pot, preferably terracotta for its porosity and weather resistance, although a glass pot can work if that's the only option available.
• Hollow Reeds: Length corresponding to the height of the vase, which will serve as chambers for the bees.
• Organic Cotton: Used to plug one end of the barrels.
• Clay or Wax: To seal the cotton and insulate the reeds.
• Rope or String: Necessary for tying the canes and hanging the vase.

How to Build a Bee Hotel: Preparing the Reeds

1. Plugging the Pipes: Take the organic cotton and tightly cap the end of each joint. Make sure the cap is tight and leaves no gaps.
2. Sealing with Clay or Wax: Seal the capped end of the pipes with a little clay or wax, to ensure there are no drafts or water ingress.

How to Build a Bug Hotel: Assembly

1. Tying the Reeds: Use string or twine to tie the reeds together. Make sure they're secure and won't move easily.
2. Inserting the Canes into the Vase: Gently place the tied canes inside the pot. If necessary, adjust the arrangement to ensure all the canes are well supported and stable.
3. Creating the Hooks: Use the remaining string to create hooks or a hanging system for the pot. This will allow you to hang the bee hotel in a suitable location.

How to Build a Bee Hotel: Placement

• Location Selection: Choose a location protected from the elements, such as under a canopy or inside a hanging fruit crate. You can also insert the pot into existing holes in a brick.
• Weather Protection: It is essential that the top of the bee hotel is protected from rain and wind to keep the reeds dry and welcoming for the bees.

Finally, don't forget to periodically check your bee hotel to ensure it's in good condition and free from pests. Annual maintenance before spring will help ensure it remains a safe and welcoming habitat for solitary bees.

The Bee "Restaurant": What to Plant Near the Bee Hotel

A bee hotel without flowers nearby is like a restaurant without a kitchen. You can build the most beautiful structure in the world, position it in the perfect spot, use the perfect reeds, but if there's no food within a few hundred meters, the solitary bees simply won't come, or they'll come and go.

Solitary bees don't have a colony to feed: each female collects pollen and nectar exclusively for her own eggs. This makes them very selective in their choice of nest: they only settle where food is abundant, varied, and accessible without wasting precious energy. The bee hotel and the flower garden, therefore, aren't two separate projects; they are two halves of the same idea.

The good news is that you don't need a large garden. A well-designed balcony, a vegetable patch, or a window box can make all the difference. What matters is seasonal continuity: solitary bees emerge from hibernation as early as February with the’Horned Osmia, and some species are active until late September. If flowering stops for weeks, that interruption translates into a gap in food availability that can jeopardize the entire breeding season.

The strategy: cover the entire season

The secret to an effective "restaurant" is the succession of blooms. A burst of lavender in July isn't enough; something needs to be in bloom from March to September, without pauses. Every plant has its own window: learning to arrange them is a small act of planning that pays off every year.

To help you build this sequence, we've collected the most useful plants month by month, with some tips on how to grow them even in small spaces.

Maintenance and Hygiene: Why a Neglected Bee Hotel Can Do More Harm Than Good

There's one thing almost no one mentions when talking about bee hotels: if left untreated, they can turn into a trap. Not immediately, and not dramatically, but over the course of the seasons, an abandoned hotel accumulates mites, mold, parasites, and unwanted insect larvae that colonize the empty corridors and put future generations of solitary bees at risk.

This isn't a reason to abandon the project. It's simply a reason to do it right.

When to intervene: respect nature's times

The first mistake people make with maintenance is intervening at the wrong time. Fall and winter are the months when larvae overwinter in the corridors: moving, dismantling, or cleaning the bee hotel between October and February means disturbing, or worse, destroying, diapausing lives that are unseen but are there. The winter silence of the bee hotel is deceptive: it seems empty, but it's full.

The right time for annual maintenance is late spring, between May and June, when all the adults have emerged. The signs are clear: the mud, leaf, or resin plugs that seal the corridors are opened from the inside by the emerging bees, leaving the cells visibly open or with the sealing materials loose. When most corridors show these signs, the emergence season is over and you can proceed.

How to clean empty hallways

Corridors that are still sealed after the spring outbreak deserve special attention. They may contain larvae that have failed to survive, unhatched eggs, or, most worryingly, colonies of parasitic mites such as Chaetodactylus osmiae, a mite specific to masonry that breeds in cells and can devastate an entire structure in a few years if left uncontrolled.

For corridors made of reeds or bamboo, the safest procedure is replacement: reeds are inexpensive and readily available, and starting over each year with fresh material is the most effective strategy for interrupting any infestation cycles. It's inexpensive, takes just a few minutes, and eliminates the risk.

For perforated wooden structures, where the passages are not interchangeable, you can use a thin brush and hot water to clean out any empty holes or any suspicious residues. No detergents or bleach are recommended: chemical residues persist in the porous wood and are detected by bees in subsequent seasons. Hot water is sufficient, as long as the structure is allowed to dry completely before repositioning, leaving it in a sheltered, sunny area for at least a week.

Protect the structure from winter humidity

Humidity is the silent enemy of a bee hotel. A structure exposed to direct rain for months accumulates moisture in the corridors, which, even without visible mold, creates an unfavorable microclimate for diapausing larvae and accelerates the deterioration of the material.

The correct positioning, with the corridor openings facing downward a few degrees so that water drains away instead of pooling, is already half the protection. The second half is an overhanging roof: a few centimeters of wood or slate above the structure are enough to deflect pouring rain.

If the bee hotel isn't protected by a fixed roof, a practical alternative for the colder, rainier months is to move it to a porch, an open shed, or under the eaves. It's not necessary to bring it indoors: the slightly cooler temperatures outside are part of the larvae's natural cycle and shouldn't be eliminated. Only stagnant humidity should be eliminated.

Checking the wooden structure once a year, before repositioning in the spring, takes no more than five minutes: check for cracks or areas of wood softened by water, and treat any degraded external surfaces with raw linseed oil, the only natural waterproofing agent compatible with bees, which does not release harmful volatile substances and penetrates the wood without forming a surface film.

A note on “too clean”

There's a paradox worth mentioning: a bee hotel that's too obsessively cleaned and renovated every year gradually loses its appeal. Solitary bees recognize previously used nesting sites through pheromones left by previous generations, a sort of chemical memory of the location that signals safety and suitability. Replacing everything every season erases this memory.

The right balance is to replace only the hallways showing real problems—mold, mites, dead larvae—and preserve those that have been in good working order. A hotel with a history is, paradoxically, more inviting than a newly built one.

FAQ

Do the bees that live in the hotel sting?

Absolutely not, you can rest assured. Bee hotel guests are solitary bees, extremely docile and gentle species that rarely sting. Unlike honeybees, they don't have a colony or large honey stores to defend, so they don't show any aggression toward humans.

Can I place a Bee Hotel on my balcony in the city?

Absolutely. Bee hotels are essential tools for urban beekeeping and urban biodiversity. Even a small outdoor space can become a vital refuge, provided there are adequate flowering plants nearby to provide the necessary nourishment.

Why don't bees come into my hotel?

If your hotel remains empty, there are usually three reasons:

1. Orientation and climateThe structure may be too exposed to wind or humidity; make sure it's in a sheltered location and with the opening facing slightly downward to allow rain to drain away.
2. Lack of “restaurant”Bees will only choose their nest if they can find plenty of food within a few meters. Make sure there are honey-producing plants nearby.
3. Technical errorsThe passages may be too short or the wrong diameter; remember that holes at least 10-15 cm deep and with a dead end are needed to make the bee feel safe.