Bee Hotels – Do They Really Work?

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Robert Pavlis

There is a great movement afoot for creating bee friendly gardens. People not only want to provide flowers, water and a habitat for the bees; they also want to provide a home for them. Lots of websites provide DIY instructions for creating these, and many companies now sell commercial products. Do bee hotels work? Which ones work better? Are there designs that will increase your chance of getting bees to move into your bee hotel?

This blog will answer all of these questions and many more.

If you think the picture below shows a good bee hotel – your wrong. It’s pretty but not good for bees.

Bee Hotels - Do They Really Work?
Bee Hotels – Do They Really Work?

Not All Bees Make Suitable Hotel Guests

I’m all for the movement to save bees, but much of this enthusiasm is misdirected towards honey bees.

Honey bee are not dying! They do not need our help in the garden. In fact, the honey bee has been shown to out compete our native bees and introduce diseases to our native bees. If you care about native bees you really don’t want honey bees in your garden.

It is the native bees that need our help.

There are also thousands of native bees and most of them will not live in a typical bee hotel. The hotels are designed specifically for bees that lay their eggs in small cavities. The most common group of these are the mason bees, in the genus Osmia. People talk about mason bees as if they are one type of bee but there are actually over 300 species found across the Northern Hemisphere.

Growing Great Tomaotes, by Robert Pavlis

Each of these species prefers slightly different habitats, so it is a good idea to research the ones in your specific location to see if the characteristics of your hotel match their requirements. For example, many species of bees nest in dead stems and will not use drilled holes.

Do Bee Hotels Work?

If the goal is to have bees nest in your hotel, then they will work, provided you have the right kind of hotel. Lots of hotels are poorly designed, or incorrectly located and don’t work very well or not at all.

If your goal is a conservation effort to protect the bees, then you will be surprised by some of the latest findings discussed below.

High End Bee Hotels

Mason bees are fussy – they don’t sleep in any old fleabag motel! If you want to create some high end bee hotels that bees will use and love, you need to meet certain criteria.

Keep Them Small

Bee condominium - leads to more pests and diseases
Bee condominium – leads to more pests and diseases

Tubes or reeds are used to allow solitary bees to lay their eggs. These also make a great place for pests to live. Both wasps and flies also find the tubes a good place to hang out and the developing bees make a great meal. Research suggests that the so-called bee condominiums, (large hotels with many compartments) will attract more pests and make it easier for diseases to spread.

This makes some sense. In nature bees must find plant reeds and use them for laying eggs. These will be spread all over the ground and if any one gets infected or attacked by a pest it will not cause harm to the other bee nests. Stacking all the reeds in one place makes it easy for pests and disease to destroy all the residents.

Plant Science for Gardeners by Robert Pavlis

Install it Properly

Position the hotel so it is facing south or south east, at least 3 feet above ground, higher is better. Don’t hide the entrance with vegetation and mount securely so it does not sway in the wind.

Replace Regularly

Replace the nesting sections when they start being covered with mold, or consistently hold parasites. Replace drilled wood blocks every two years. This is one reason many people prefer using reeds or rolled up paper that can easily be replaced.

Use Good Reeds

The reeds you use must:

  • be the right size
  • be free of splinters inside
  • have the end closed
  • allow moisture to exit (ie no plastic or glass)

If you use natural plant reeds, the ends should be cleanly cut with no splinters and no cracks.

The use of reeds or rolled up paper is much better than drilled blocks of wood since they can be easily replaced each year, reducing the chance of spreading disease.

Dry and Wind-free

The bee hotel should have an overhanging roof, so the nesting bees stay dry and out of the wind. Few commercial products meet this requirement.

Keep Birds Away

Woodpeckers and other birds may attack the hotel looking for a quick meal. If this is a problem, cover the entrance with wire mesh, keeping it an inch or so away from the openings of the holes.

Maintenance and Care of Your Bee Hotel

Commercial products and many websites make it sound so simple to provide a bee hotel. Buy or make the product, mount it, and stand back to watch your bees. Following this advice will almost certainly lead to disappointment and dead bees.

It is critical to maintain and clean the bee hotel. David Coles, a volunteer at the Bumblebee Conservation Trust, gives this advice; “The single most important thing with a bee hotel is that it should be cleaned out every year, all the pupae removed and cleaned as well and then presented for release the following year. Otherwise your bee hotel will become infested with parasites and full of nothing but dead bees.”

After bees have emerged from the hotel, clean out the holes or remove the reeds. Everything should be empty and clean before new bees start laying their eggs. In fall, store the hotel in a cool, dry, safe place such as a garden shed. Return them in early spring.

Some people open all the reeds in winter and remove living egg cocoons so that they are easier to store. The bee hotel can then be prepared for spring.

All this work – now you know why they call it a ‘hotel’!

Is it a Good Conservation Tool?

Male red mason bee, Osmia bicornis
Male red mason bee, Osmia bicornis

Do bee hotels conserve native bees? Bee hotels can be fun and educational, but are they any good at preserving bees? That question has not been researched very much, but there is one good study out of Toronto, Canada (ref 2), that looks at this specific question.

From May to October, 2011–2013, 200 bee hotels were set up each year throughout the Toronto area, providing a total of 600 hotels for the study. Cardboard tubes of various diameters were used. “At the end of the season, the tubes were collected, marked and placed in storage to overwinter at 4°C. In April of the following year brood cells were moved to a sealed incubation chamber kept at 26°C and 60% humidity until adult emergence. They were then sexed and identified to species, and opened for examination. “, ref 2.

Results:

  • On average each hotel produced 45 insects.
  • 31 species of pollinating bees were found, which represents 52% of all cavity-nesting species in the area.
  • 10% of the bee species were non-native, representing 37% of the bees reared.
  • Broods produced were 2,500/year of native bees and 6,000/year of all others (non-native bees and wasps, and native wasps).
  • Wasps used the site more than bees.
  • Hotels located in gardens had a higher ratio of native bees than non-garden areas.

Bee hotels certainly work for rearing insects, but they should probably be called Wasp Hotels. Keep in mind that many of the wasps are also important predators in the garden so their presence in hotels in not a bad thing. However, some wasps are also parasitic to bees.

The wasps found in the hotel do not generally sting and are not your common yellow jackets or paper wasps.

Bee hotels do not help native insects more than non-native ones.

Among all the bees and wasps reared, 38 percent were native wasps, while only 28 percent were native bees. I wondered how this compared to populations that do not have access to hotels? Are hotels affecting the ratio?

I contacted one of the authors, Scott  Maclvor and here is his reply to my questions:

How does the population of bees and wasps in the hotels compare to similar areas without the hotel?

“This is an impossible question because the sampling method I used involved the nest itself. Sampling with nets or pans alone could be used to give an estimate, but couldn’t be used in conjunction with nest boxes because the colonizers would be confounded (by the pans/nets). Cavity-nesters only represent about 25% of bee species in any single habitat – the rest live on or underground. Factoring in the bulk of bee communities (and wasp communities for that matter) would greatly change the answer to this question.”

If the ratio of wasps to bees is the same with or without hotels, then the wasps using the hotel are not really a problem.

“Wasps using the hotels never were a problem in the first place! Cavity-nesting wasps are wonderful – they play essential roles as predators of abundant invertebrates including some pests.

If the numbers are higher than without a hotel, then there is some value to the hotels. I think that a comparison to natural numbers would be informative.

I think overall hotels are fine and enjoyable to observe. Marketing them for profit in order to ‘save the bees’ is false.”

Best Design for a Bee Hotel

What is the best design for rearing native bees? This has been studied extensively and details are found here.

Bee Hotels – Do They Really Work?

It is clear bee hotels do work if you use the right kind, and maintain them correctly. Occupants will consist of both bees and wasps, but both are good for the garden.

As a way to protect bees, it probably has limited value because attracting a lot of bees to one location may result in the increased spread of disease.

One of the issues with gardens is that much of the dead plant material is cleaned up in spring. If plant reeds are removed, then cavity-breeding bees may not have places in the garden to nest. In this case small bee hotels can be a benefit.

  1. Insect Hotel, Refuge or Fad?; https://entomologistlounge.wordpress.com/2017/09/18/insect-hotels-a-refuge-or-a-fad/
  2. Bee Hotels’ as Tools for Native Pollinator Conservation: A Premature Verdict?; http://www.conservationmagazine.org/2015/03/bee-hotels-have-unwanted-guests/
  3. Attract mason bees; https://www.ecolandscaping.org/03/beneficialspollinators/attract-mason-bees-no-protective-gear-needed/
  4. Image source for Red mason bee; gailhampshire

 

 

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

22 thoughts on “Bee Hotels – Do They Really Work?”

  1. Thanks for all this info. I would like to buy or build a nest box for carpenter bees. In spring they fly around our treated decks looking for suitable housing. Any recommendations?

    Reply
    • “the point about pine cones in your first reference has been discredited” – willing to look at the links to support this statement.

      Reply
  2. Hello! Very interesting article.
    When is the best time to install a bee hotel? Now is end of May, can I still install one?

    Reply
    • I don’t think it matters. If you are trying for a particular type of bee it needs to be in place before they look for a home.

      Reply

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