Bee-hotels seem like a win-win, they provide wild bees with a place to nest and the bees will in turn pollinate your garden. Unfortunately, it is not so straightforward as it may sound. Some scientist and nature conservation organizations warn that bee-houses can do more harm than good. In this article, we will provide you a neutral source of information, so everyone can form his own informed opinion about this topic.
Declining bee numbers are reported throughout the world [1,2]. This alarming trend caused various organizations to act, at Vatorex for example we aim to support honey bees (see savethebees.ch what you can do to help!). Beside honey bees many other bee species can use some help . Wild bees are very efficient and important pollinators and their loss can’t be replaced  (Read more about the difference between wild bees and honey bees here).
Various organizations and people aim to support wild bees, which is great! An often mentioned solution is buying a bee-house or bee-hotel where wild bees can build their nests. As they are also great pollinators they also bring more life to your garden. These bee-houses are however not free from controversy.
To set the record straight, bee-houses are not for all bees. They are typically (although not only) used by mason bees and mason bees are not endangered . 70% of all wild bees build their nest underground and are not interested in any form of bee-house . Therefore, if your goal is to support wild bees, you are best off by creating a bee-friendly garden. Plant different types of flowers, which blossom in different periods during the year, use few (or even better, don’t use) pesticides, and leave some areas undisturbed.
However if you want to improve the pollination in your garden, or just like to have bees buzzing around, a bee-house is an excellent way to achieve this. Mason bees are excellent pollinators and would enhance your own planted fruit, vegetables and/or herbs for sure!
Most wild bees are solitary bees, the mason bee is no different. Bee-houses put them unnaturally close together. This can have various negative effects.
«The cheek-to-cheek occupancy of bee houses helps predators (woodpeckers for example), parasites (including wasps, mites, and others), and diseases find a dense host-bee population to exploit.» says Eric Mader, co-director of the pollinator and agricultural biodiversity program at the Xerces Society for Invertebrate Conservation .
To counter this, one should clean the bee house every year to prevent parasites and bacteria to dominate the nest. This cleaning should be done in spring, when all the larvae have grown into bees and have left the nest. Furthermore, the material of the bee-house greatly influences it’s suitability for bees. Bamboo for example, is known to contain moisture much more compared to other wood types. This will create a very humid bee nest in which harmful pollen mites can thrive. Another issue is how the bee house is placed. When not attached properly, wind can cause the bee house to shake, which replaces the larvae away from their food source and cause them to starve. In sum, care has to be taken when buying a bee-house. According to evolutionary biologist Colin Purrington, «If the above sounds like way too much maintenance, don’t buy a mason bee house. Get a garden gnome or a gazing ball». If you want to learn more about how to install and maintain a bee-house, Purrington has created a list of things to keep in mind, which you can find here.
Wild bee sponsorship
Another option is letting someone else do the maintenance for you. For example, at Wildbiene + Partner one can buy a ‘Wildbee sponsorship’. Here you get a bee-house together with a start population of mason bees. After the growing season you can send your bee-house together with the larvae back to the company and they will do the cleaning for you. Next spring you receive a new start-population of bees and the cycle starts again. The additional bees that have grown out of the nest will be used on orchards for pollination.
This initiative sounds great at first glance, but is also not free from controversy. Wild bee conservation organization WildBee.ch published an extensive list of arguments of why one should not buy such a bee-house. This caused Wildbiene + Partner to respond. Below we tried to shed some light about some commonly raised themes.
WildBee.ch and Wildbiene + Partner
WildBee.ch is critical on the motivations of Wildbiene + Partner, does not support wild bee conservation and raises concern over the well-being of the used bees. Claims from both sides are not always supported with sources which often pitches the word of WildBee.ch against the word of Wildbiene + Partner.
A main point of criticism is that the initiative of Wildbiene + Partner does not support wild bee conservation while this impression is given. Just like regular bee-houses, mostly the non-endangered mason bees will nest there. Wildbiene + Partner also acknowledges this. «Mithilfe der Bevölkerung können wir die Bestäubungssituation in der Schweiz verbessern. Dass dies mit Wildbienenschutz nicht direkt etwas zu tun hat, ist uns klar und wird von uns auch nicht behauptet.» says Anna Schmidhalter working in the marketing department of Wildbiene + Partner .
However Wildbiene + Partner also has other projects which are focused on conservation. Namely by creating bee-friendly gardens and educational projects about wild bees. So, indirectly revenue from the sell of the bee-houses might be used in projects to supports wild bees. The bee-houses themselves however do not contribute to wild bee conservation.
WildBee.ch, as being a non-profit organization does not support the commercial interest of Wildbiene + Partner. They argue that Wildbiene + Partner solely tries to make money from selling the mason bees to farmers and let people do the work for them by breeding new mason bees.
Mason bees are excellent pollinators of orchards and it are exactly these species that is mostly used the bee-hotels. Also, scientific studies show that most orchards do not naturally attract enough mason bees for pollination.
«These results indicate the potential of O. bicornis and O. cornuta as efficient pollinators in intensively managed fruit orchards. However, intensive fruit orchards appear less suitable as habitats for these mason bees to establish an endogenous pollinator population. Hence, the introduction and management of mason bees in orchards will improve pollination.» Says Schindler and Peters of the Institute of Crop Science and Resource Conservation (INRES), University of Bonn.
However this does not imply that Wildbiene + Partner just tries to make money. Other activities show that they also put time and resources into conservation projects.
Well-being of the bees
Another issue is the safety of the bees, for example how does the transport by post affect them? Here is no conclusive answer to give as both sides do not offer much evidence whether it would or wouldn’t harm the bees. Wildbiene + Partner argues that there is no harm, as the bees are sleeping in a cocoon during the transport. An American study showed that female mason bees who were transported by mail were just as productive as mason bees who where not transported . However this study was done with a different type of mason bee that is present in the United States. No data of the O. bicornis and O. cornuta exist. WildBee.ch cites another study which showed negative affects during shipping, however this was done with honey bees, who in contrast to mason bees do not sleep during winter and can therefore not be compared . So, there is little knowledge how shipping by mail affects the mason bees.
Another issue is the use of mason bees on fruit farms and how they are affected by pesticides. Wildbiene + Partner argues that it is not allowed to use pesticides during blossom period, however this does not mean that bees are not exposed to pesticides. Residues of pesticides will remain in the plant and bees can also be affected by pesticides after the pesticide was actually sprayed .
Buying a bee-house will definitely improve the pollination in your garden but not necessarily supports bee conservation. In order to have healthy bees buzzing around in your garden, some time has to be dedicated to the maintenance of the bee-house. Letting someone else do the maintenance for you sounds great, but this solution is not free from controversy. All in all, inform yourself if you consider buying a bee-hotel. With the right care a bee-house might be great addition of your garden.
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