Building a bee hotel for wild bees

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  • A bee hotel is a nesting aid for wild bees.
  • Building a bee hotel yourself is super easy and doesn't cost a lot of money.
  • With the right material, location and timing, nothing can go wrong with your bee hotel.

It's not just us humans who have an acute shortage of living space in Germany. Many wild bees are also looking for a suitable home where their offspring can grow up protected. However, a lot has happened with bees in recent years and in many places bee hotels line field paths or stand in gardens and balconies. Whether in DIY stores, on the internet or even at discount stores: Bee hotels, which are actually called nesting aids, are now available to buy almost everywhere. With good and sensibly built bee hotels, it usually only takes a few days for the first wild bees to make themselves at home. Unfortunately, however, the majority of bee hotels on the market are poorly made, built with the wrong materials or constructed in a pointless way.

There are many reasons for these "bad" bee hotels: cost-cutting, ignorance - and sometimes even rip-offs. It is actually very easy to make a luxury 5-star bee hotel yourself. All you need is some knowledge about wild bees, a few inexpensive materials and a little bit of craftsmanship.

Name Wild bee
Animal class Insect
Latin name Apidae
Higher classification Hymenoptera
Food Nectar and pollen
Common species in Germany Horned mason bee, red mason bee, silk bee, bumblebee, blue wood bee

Bienenhotel bauen – Anleitung mit Tipps und Tricks: Was passiert in einem Bienenhotel?

To ensure that your bee hotel is colonized, you should know the following before you start building: Bee hotels are colonized by wild bees and not by honey bees. The majority of wild be es are solitary bees and do not live in a colony, which is why female wild bees have to look after their offspring themselves. Although there are relatively few wild bee species that colonize nesting aids (most nest in the ground), it is amazing how quickly well-built bee hotels are accepted.

Around 19 percent of wild bee species nest in existing cavities and are happy to accept bee hotels as nesting aids. But what actually happens in a bee hotel? Female wild bees lay eggs in the cavities of a bee hotel, then stuff plenty of food in the form of pollen and nectar inside and finally seal the brood cell with soil. It usually takes a whole year before the baby bee is ready for the outside world. In the meantime, the larva hatches from the egg and then fills its stomach with the delicious pollen. After a few months, the larva pupates in a process known as metamorphosis and then transforms into a wild bee. In spring, the wild bee finally hatches from the brood cell and sees the light of day.

What materials are suitable for a bee hotel? Dos and don'ts

Understandably, wild bee moms are quite demanding when it comes to choosing their brood cells: after all, this is where their offspring grow up and it should therefore always be dry and safe from predators. In addition, the cavities must be the right size and there should be food sources in the immediate vicinity - a bee hotel without bee-friendly flowers nearby is guaranteed not to be colonized!

But which materials are suitable for a wild bee hotel? Many commercially available bee hotels contain a variety of different materials: pine cones, straw or snail shells. Unfortunately, such nesting aids are not suitable for wild bees. On the contrary: pine cones attract earwigs, for example, which in turn eat the eggs and larvae of wild bees.

Hollow plant stems, cardboard tubes, clay bricks or pieces of hardwood with holes, on the other hand, are ideal for building a nesting aid. However, not only does the material itself have to be suitable, but the workmanship must also be neat and tidy. In his book "Ready to move in: nesting aids for wild bees", wild bee enthusiast Werner David expertly explains what the perfect wild bee hotel looks like.

 

Suitable material for wild bee nesting aids: Hardwood with holes

When processing hardwood for a wild bee hotel, we follow a model from nature: feeding galleries of beetle larvae in dead wood. In the wild, many wild bees and wasps colonize the former feeding galleries of longhorned beetles in dead tree trunks. These include the rusty mason bee, the horned mason bee, the buttercup scissor bee and the common hole bee. There are a number of reasons why hardwood is ideal for building bee hotels. Unlike softwood, cracks are less likely to form in hardwood and the wood does not resinify as much as softwood. If the wood is very cracked, fungi can colonize the cavities. The resulting mold could then infest the wild bee larvae and make them sick or even kill them.

Another advantage of hardwood is the material density: as hardwood has a higher density than softwood, the wood fibers are closer together. This is very important as the fibers splinter less. Many wild bees enter cavities backwards so that they can then strip off pollen and nectar more easily. If wood fibers and splinters protrude into the tunnels, a wild bee could slash its wings - this would be certain death for it and its offspring. In nature, wild bees instinctively avoid such tunnels; therefore, such softwood cavities are rarely or never colonized. With cleanly drilled hardwood holes, no splinters protrude into the tunnels so that wild bees can crawl into them safely.

Before you start drilling, you first need to find suitable wood. Ash is particularly suitable for wild bee hotels as there are hardly any cracks in the wood. However, there are also many other types of wood that are ideal for bee hotels.

  • Maple
  • Apple
  • Birch
  • Pear
  • Oak
  • Ash
  • Hornbeam
  • Hazel
  • Chestnut
  • Plum
  • copper beech
  • Elm

When looking for wood, you must also consider the following points: The wood should be dried, debarked and untreated. Wet wood could start to mold, which would make the wild bee larvae sick. You must remove the tree bark as it could attract predators of wild bee larvae. In addition, your piece of wood should be about 10 to 20 centimetres deep, as our holes will be at least 10 centimetres deep.

Building a bee hotel: How to use hardwood for your nesting aid

So bitte nicht! Bohrungen für Bienenhotels sollten immer quer zur Faser verlaufen. In diesem Bild wurde parallel zur Faser gebohrt © Michael Gaida/Pixabay.
So bitte nicht! Bohrungen für Bienenhotels sollten immer quer zur Faser verlaufen. In diesem Bild wurde parallel zur Faser gebohrt © Michael Gaida/Pixabay.

If you decide to use hardwood elements in your bee hotel, it is very important to work carefully. Improperly drilled holes are rarely colonized and in some cases wild bees can sustain life-threatening injuries. Therefore, every drill hole should be splinter-free, fiber-free and clean.

This is what you need if you want to use hardwood in your bee hotel:

  • A piece of hardwood with a depth of at least 10 centimeters
  • Drill or cordless screwdriver
  • Sharp (wood) drill bits in various sizes from 2 to 10 millimeters
  • Sandpaper and file

For wild bee hotels, it is important that your drill holes are perpendicular to the wood grain. This means that you do not drill parallel to the annual rings, but at right angles to the bark.

 

As long as you pay attention to these points, you can be completely free with patterns and arrangement - so let your creative side run wild! Patterns (or an asymmetrical arrangement of the drill holes) help the wild bees to find their way later during the approach.

So take your piece of hardwood, draw your pattern on it and then you can start drilling. Please be patient with your drill: even with sharp drill bits, it can take a while to drill the holes. Your drill holes should be at least 2 millimeters and no larger than 10 millimeters. Depending on how large your piece of wood is, you can drill between 8 and 10 centimeters deep - but please always remember to drill across the wood grain!

Once your holes have been drilled, you can tap them out or vacuum them out with a vacuum cleaner. Now take a look inside your drilled holes and see if there are any splinters or chips. If so, please take a small file or a rolled up piece of sandpaper and remove the sharp splinters.

Once your drill holes are all clean, free of splinters and fibers, your hardwood piece is ready for its first guests. Take your piece of wood and place it in a sunny place, protected from rain and wind. Of course, you can also use your piece of hardwood as an element of a larger bee hotel; or you can put a (water-repellent) roof on your piece of wood.

Suitable material for wild bee hotels: Hollow plant stems

Hollow plant stems are also colonized by many solitary wild bees. Bamboo, reeds or straws are particularly popular and are usually colonized relatively quickly. But there are also a few points to bear in mind with hollow plant stems!

As with hardwood, the hollow spaces must also be clean and splinter-free. The plant stems should therefore not be brittle, thin or frayed. When processing them, you must therefore ensure that the entrances are not crushed and have a clean opening. When choosing your stems, you should only use those with an internal diameter of 2 to 10 millimetres, as wild bees do not colonize larger cavities.

With hollow plant stems, which you should always install horizontally in your bee hotel, you must also remove the plant pith. In 99 percent of cases, the pith is no longer present in dried stalks - if it is, you can remove it with a screw or other pointed object. Please also make sure that your stalks are only open on one side, otherwise only mason bees will dare to enter your bee hotel. You can either seal the individual stalks from behind with plaster, wax or clay; or you can push them against a straight surface at the back, for example a wooden board: this is the quickest and easiest way.

Bamboo and reed for bee hotels: how to use the filling material

Bamboo is great for building wild bee hotels - and in the best case, you can even get it for free! Perhaps you or someone you know has bamboo in their garden; if not, you can also find bamboo cheaply at the DIY store. It's best to use a fine hacksaw to cut your bamboo to the right length: This way, the bamboo won't fray so much and you won't have to do so much sanding later.

Reeds are also suitable for bee hotels, although they are a little more difficult to work with as reed stems are often brittle and fibrous. If you don't have any reeds in your garden, you can of course also use reed mats from the DIY store. Please use very sharp tools, such as sharpened garden shears or saws. You must also ensure that the entrances to the reeds are free of sharp fibers to prevent bees from injuring themselves.

Hollow plant stems as filling material for nesting aids

Once you have prepared enough bamboo, reeds or other hollow plant stems, you can simply stack them up in your bee hotel. There are no limits to your imagination here, as you can use pretty much anything as a housing for your bee hotel: Empty tin cans, PET bottles or a classic wooden box. Just make sure that you put enough tubes in your bee hotel so that they are firmly wedged together and don't fall out.

 

Mit hohlen Pflanzenstängel lassen sich sehr pragmatische Bienenhotels bauen © Herbert Bieser/Pixabay
Mit hohlen Pflanzenstängel lassen sich sehr pragmatische Bienenhotels bauen © Herbert Bieser/Pixabay

Other suitable filling materials for nesting aids: Pithy plant stems

Of course, there are many other suitable filling materials for nesting aids. For example, there are plant stems containing pith, such as blackberries. There are wild bee species that do not nest in existing cavities, but gnaw their own passageways. If you also want to use pithy plant stems for your bee hotel, you must ensure that they are always attached vertically to your nesting aid, otherwise they will not be colonized.

Not every plant species is colonized by wild bees, so you should use the following list of plants as a guide:

  • Mugwort
  • blackberries
  • thistles
  • dog rose
  • Motherwort
  • raspberry
  • Elderberry
  • Burdock
  • Mullein
  • Sunflower

It is best to hang such plant stems individually, vertically and without ground contact. Of course, you can also attach the stems to the garden fence or a post to create a mini bee hotel.

Deadwood: The most living filling material for bee hotels

Even if the name doesn't suggest it, deadwood is perhaps the most living filling material for bee hotels. Numerous species of wild bees love dead wood and gnaw their own nest tunnels in it. The white rotten deciduous wood is particularly suitable as a nesting aid for wild bees. The endangered blue-black wood bee is a frequent guest in dead wood and will thank you for it!

 

Ein toter Baumstumpf beherbergt viele Wildbienen und andere Insekten © Markus Baume-ler/Pixabay

Suitable types of wood for deadwood elements are

  • Ash
  • oak
  • maple
  • Beech
  • Fruit trees
  • Willow
  • poplar

However, you should bear in mind that deadwood elements in your bee hotel need to be quite large: The piece of deadwood should be at least 30 centimeters or even larger. Deadwood is therefore less suitable for small insect hotels.

How do you build a bee hotel? Tips and tricks for building nesting aids

Once you have your filling materials together, you can build a bee hotel in no time at all! You basically have two options: Either you build a bee hotel from scratch; or you follow the upcycling principle and use something old and breathe new life into it. Both options have their advantages!

Whether PET bottle or elegant wooden box; whether fist-sized or two meters high: there are no limits when building bee hotels. As long as you use the right filling material, there's not much that can go wrong. Of course, you can also mix different filling materials in a bee hotel : this can also create aesthetic works of art!

The only thing you should pay attention to is that your bee hotel is protected from wind and weather. A water-repellent - or water-draining - roof is essential. Sheet metal, plastic or even a sloping wooden board are ideal for this.

Common mistakes with bee hotels: Incorrect material and poor workmanship

Unfortunately, there are many negative examples of bee hotels. At best, these are not even colonized by wild bees - at worst, the wild bee larvae die in them. Whether in DIY stores or supermarkets, poorly constructed bee hotels can be bought (almost) everywhere these days. If you don't have time to build your own bee hotel, you should therefore pay attention to the following points.

Incorrect filling material is one of the most common mistakes made with nesting aids: Whether straw, pine cones, snail shells, perforated bricks or plastic straws - these materials have no place in a wild bee hotel. There is no species of wild bee that nests in straw or pine cones as they cannot find shelter here. Other insects, however, feel right at home there: earwigs often spend the night in pine cones and then devour wild bee larvae and eggs for breakfast, which completely destroys the purpose of a bee hotel. Some wild bee species do nest in snail shells, but only if these are on the ground and can move freely.

Perforated bricks are not suitable for a wild bee hotel due to their sharp edges. As soon as a wild bee tries to climb into a perforated brick, it can injure its wings and no longer be able to fly. But you can remedy this: Take your prepared reeds or pieces of bamboo and fill the cavities of the perforated bricks with them.

However, it is not only the filling material that is botched up, but also the workmanship. The most common mistakes made when making bee hotels are drilling the wrong holes: Many run-of-the-mill bee hotels contain whole logs that are drilled from the front side. Several mistakes are often made here: Instead of hardwood, softwood is usually used; the holes are drilled parallel to the wood fiber and not across; the holes are not drilled cleanly and the holes are full of splinters. Often there are also many cracks in the wood where moisture can accumulate.

Where do you put up a bee hotel? Location and installation of nesting aids

To ensure that your bee hotel is well visited, you need to consider a few factors when choosing a location.

  • The location for your bee hotel should be sunny and dry.
  • Wild bees should have an abundant food supply in the immediate vicinity.
  • Your bee hotel must be securely attached and free of obstacles.

The ideal orientation for a bee hotel is from south-east to south-west, as this is where you get the most hours of sunshine. The warm rays of sunshine ensure that your nesting aid always stays nice and dry and thus protects against fungal and mold infestation.

It is also important that you do not place your bee hotel directly on the ground. It is much better to hang your nesting aid or place it on a shelf. What you should not do, however, is tie your bee hotel to a string and leave it hanging freely. Wild bees hardly ever colonize such nesting aids.

If you set up your bee hotel somewhere where there are lots of birds, you should build a protective structure. Because tits and the like like to treat themselves to a protein-rich bee larvae snack! To prevent this, you can stretch chicken wire in front of your insect hotel, which will prevent birds from eating the wild bee larvae.

When should you put up a bee hotel? Wild bee year at a glance

To anticipate one thing: There is no wrong time to hang up a bee hotel. The worst that can happen is that it takes a little longer for your nesting aid to be colonized. Even if there is no wrong time, you can set up your bee hotel at a favorable time. It makes sense to set up a nesting aid shortly before the first wild bees hatch so that they have a breeding site right away.

Depending on the weather, the season starts at the end of February or beginning of March and lasts until the end of September. The different species of wild bee breed at different times, so it makes sense to set up your bee hotel in February and then leave it up all year round. This way you can offer a nesting place to as many different species of wild bees as possible.

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