Every year at least one female Stelis punctulatissima [1] is active on the bee hotels. Sitting in the opening she uses her antennae to smell whether one of her target hosts occupies the nest cavity. Some she enters but it has not been clear so far if the target hosts are nesting in them. Regularly she can be found resting in the opening observing the outside world.
Literature
1 Nederlands Soortenregister