You may be wondering what bees need a hotel for, when they make their own hives. The truth is that many species of bees are solitary - they do not live in hives but instead construct their own nest. The main reason for this is because in these species every female is fertile and this would not make for comfortable communal living in a hive.
Bee hotels are necessary for a number of different reasons. Bee populations have been on a decline in recent years. Part of the problem is that their natural habitats have been cleared to make way for intensive agriculture. Pesticides have also been instrumental in their decline.