Putting up a wild bee or insect hotel does not contribute to biodiversity. The reason is simple: the usual nesting aids provide housing for cavity-nesting wild bees, that is, for species that build their nests in existing cavities. They account for 5 per cent of all native species. Many of them are not threatened at all and need no support. Only rarely does a threatened species find its way into a bee hotel.
The benefit lies elsewhere: you can conveniently watch a few mostly common species nesting. That is no small thing – but it is nature observation, not species conservation. And it is not only bees that are attracted, but also wasps, beetles and other arthropods.
Pre-stocked hotels with so-called starter populations are a real problem. We advise against them.
Anyone who genuinely wants to support wild bees starts with nesting sites and food – for the species that actually occur locally. The Bee-Finder shows which those are.
In detail on the page Wild bee hotels.