Insect hotels: useful or greenwashing?

Key takeaways

The verdict is nuanced: insect hotels can be true sanctuaries for biodiversity, but on the strict condition that they are well-designed, well-placed, and well-maintained. The vast majority of commercial products do not meet these criteria and function primarily as decorative objects.

The 3 major problems with commercial hotels:

• Poor materials mixed illogically (pine cones, straw, bricks) which in reality do not host any targeted species.
• Unsuitable stem diameters (too wide, too short, poorly cut) that do not meet the needs of solitary bees.
• Poor installation (north orientation, too low, too humid) which makes the habitat inhospitable.

The good news: a simple, well-designed, well-placed hotel — or even a wild corner of the garden — can host dozens of species of solitary bees, auxiliary wasps, and other essential pollinators. You just need to know the rules.

Why insect hotels have been so successful

Before criticizing, let's understand where the enthusiasm comes from.

In the early 2010s, faced with the massive awareness of pollinator decline, the insect hotel emerged as an accessible ecological gesture. No need to be a beekeeper, no need to know about biodiversity, no need to tear up your lawn: you buy an object, you hang it up, you've done your part. The market exploded.

The success is also visual and symbolic: a large insect hotel in a garden is a social signal ("I care about the environment"), an interesting decorative object, and an educational tool for children.

The problem is that industrial manufacturing quickly took precedence over entomological knowledge. The result: aesthetically pleasing, well-marketed objects, but designed without considering the real needs of the targeted species.

The 5 recurring mistakes of commercial hotels

Mistake 1: The useless mix of materials

The majority of hotels sold mix in the same structure: bamboo, pine cones, straw, perforated bricks, bark, planks. It looks nice in photos, but in reality, each material targets a different family of insects, and many target nothing at all.

• Pine cones: supposed to host lacewings and ladybugs. In practice, these species rarely use them in France.
• Loose straw: supposed to host earwigs. In practice, it rots quickly and becomes a breeding ground for mold.
• Perforated bricks with large holes: too wide for solitary bees, too small for anything else.

Result: 80% of the surface of a classic insect hotel is useless.

Mistake 2: Unsuitable stem diameters

This is the most technical, but most crucial, mistake. Solitary bees — which are the real beneficiaries of a good hotel — have very specific needs:

• Stem diameter: between 4 and 8 mm (mason bees, leafcutter bees)
• Depth: at least 10 to 15 cm
• Stem closed at the back (not a through tunnel)
• Clean cut (not crushed or split)

However, many commercial hotels use bamboo that is roughly cut, open-ended, or has random diameters. Bees pass by, observe, and look elsewhere.

Mistake 3: Whimsical orientation and height

An insect hotel needs:

• A south or southeast orientation (solitary bees are thermophilic)
• A height of 1 to 2 meters from the ground
• Shelter from rain (overhang or roof that extends)
• Protection from prevailing winds

However, we see hotels hung in the north shade of a wall, 30 cm from the ground, in strong wind. No chance a solitary bee will lay eggs there.

Mistake 4: Total lack of maintenance

An insect hotel is not a decorative object "placed for life". It is a living habitat that requires regular maintenance:

• Replace colonized stems every 2 to 3 years (to prevent parasites and mold)
• Clean empty compartments
• Monitor for parasite attacks (mites, parasitic flies)

Without this, the hotel becomes a trap: laid eggs are systematically parasitized or moldy. It's even worse than no hotel at all, because eggs are concentrated in one place.

Mistake 5: The false argument "for bees"

Many hotels are sold with a honey bee image on the packaging. However, honey bees NEVER settle in an insect hotel: they live in colonies in a hive, not in individual cavities.

Hotels actually host solitary bees (mason bees, leafcutter bees, carder bees...), parasitic wasps (useful in the garden), and some beetles. Precious species, but completely different from the image sold.

The scientific verdict: useful, but with conditions

Several European entomological studies, particularly those conducted by the Bee Observatory and MNHN researchers, have analyzed the actual occupancy rate of insect hotels. Main conclusions:

• Well-designed hotels show an occupancy rate of 60 to 90% by solitary bees
• Non-selective commercial hotels show an occupancy rate of 10 to 30%, mainly by a few opportunistic species
• A large portion of the compartments never serves any purpose, regardless of the observation time

Conclusion: the insect hotel is not greenwashing by nature, but the majority of commercial products available fall into this category due to design flaws. A good, well-designed, and well-placed hotel is a true biodiversity sanctuary.

How to build or choose a good insect hotel

Good news: an effective hotel is simpler to build than to buy. Here are the criteria.

Materials that actually work

For solitary bees (the real stars of the hotel):

• Bamboo stems neatly cut, closed at the back, various diameters from 4 to 8 mm
• Hollow stems of elder, reed, knotweed cut into 15 cm sections
• Drilled logs: holes 4 to 10 mm, depth 10-15 cm, spaced 2 cm minimum

For auxiliary wasps (useful in the vegetable garden):

• Bramble or raspberry stems (the pith attracts certain species)
• Fine holes of 2 to 4 mm in logs

For beetles and others:

• Pile of dead wood on the ground, nearby (more effective than integrated into the hotel)
• Stacked stones in a corner of the garden

The right location

• Orientation: full south or southeast
• Height: 1 to 1.5 m from the ground
• Shelter: roof extending 5-10 cm to protect from rain
• Stability: securely fixed, must not move in the wind
• Environment: near flowers and melliferous plants (otherwise, no interest)

The ideal size

Surprisingly, a small, well-designed hotel is better than a large hodgepodge. A 30 x 30 cm frame with 2 or 3 well-chosen materials will be much more effective than a 1-meter furniture piece with 10 different compartments.

Minimal maintenance

• Visual inspection in spring: remove damaged or moldy stems
• Partial renewal every 2 to 3 years
• Gentle cleaning of empty compartments
• Discreet observation in May-June: this is when solitary bees come to lay eggs, magical to observe

The most effective alternative: letting nature take its course

Here's the truth no one tells you in garden centers: the best "insect hotel" is often a wild corner of the garden.

• A pile of dead wood in a corner hosts beetles, earwigs, hedgehogs
• A dry stone wall harbors solitary bees, lizards, bumblebees
• An unmown area with nettles, brambles, yarrow feeds dozens of species
• Old dry stems of fennel, cardoon, burdock left standing shelter dozens of species during winter

Cost: 0 euro. Effectiveness: maximal. Maintenance: none.

It's less photogenic than a large wooden insect hotel, but ecologically, it's incomparable.

And the Asian hornet in all of this?

A quick aside to close the loop. When you install an insect hotel or create a wild corner of the garden, you attract and concentrate dozens of pollinator and auxiliary species.

However, the Asian hornet hunts these species: solitary bees, hoverflies, butterflies, native wasps. All its meals. The richer your garden is in biodiversity, the more it becomes an attractive hunting ground for this invasive predator.

It's paradoxical: by doing the right thing for biodiversity, you also attract its main enemy in France. A selective hornet trap then becomes the logical complement to a garden welcoming to pollinators. It intercepts hornets without harming the species we are trying to protect.

In summary: an insect hotel yes, but not just any one

The insect hotel is not a myth, but it is not the miracle solution that is sold to you either. Like many ecological objects, it depends entirely on the quality of design and use.

If you really want to benefit your garden's biodiversity, two options are available to you:

1. Build or choose a small, well-designed hotel, with targeted materials, well-placed, and maintain it
2. Leave a corner of the garden wild: it's free, no maintenance, and it works best

And ideally: both at the same time. With, as a summer complement, a selective trap to intercept the Asian hornet that threatens all this small world.

The true ecological gesture is not the object you hang on the wall. It is the attention you pay to living things.

Bzzz see you soon, Buzette.

Want to protect the pollinators you welcome into your garden? Discover Hornet EcoTrap, the selective trap made in France that targets only Asian hornets, without harming solitary bees, bumblebees, and other auxiliaries.

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Do you have an insect hotel at home? Share in the comments the species you've observed there — it's always fascinating to discover who lives in our gardens.

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