The bug hotel opened in the spring of 2017, offering superior accommodation and personalized services in eight spacious yet cozy 9mm by 90mm holes drilled in healthy, un-treated, pinewood that’s easy to chew through should guests wish to make modifications to the otherwise comfortable cylinders.
The particularity of this property is that one of the outer walls has been replaced by crystal-clear 6mm glass that offers spectacular views. Privacy is ensured by a hinged flap that swiftly closes when so desired.
The official designation of the property is CB-890, because you can see the bee in all 8 rooms that measure 90mm in length.
It lies just outside my window, by some flower pots next to the wall (SE) It was populated every year, starting in early spring, with the holes sealed by May. The highest number of holes occupied must have been 5 or 6. Last year (2021) was the lowest so far with only 3 taken.
The tenants are solitary bees of various species, and there are, of course, various parasites that treacherously prey on their larvae.
This pretty cigar-looking structure is made by the leaf-cutter bee:
These are made by what I believe to be mason bees:
A whole row of cocoons has been killed by the larvae of the Carpet Beetle. They manage to break the cocoon, get inside and feed on the larva.
The life cycle is as follows: there is frenetic activity in early spring, when females find (or make) a hole in a vertical structure, usually wood, and fill it up with several mounds of pollen. The bee then lays an egg on each mound, separates them with little walls of mud and seals the entrance. The egg becomes a larva that feeds on the pollen and builds a cocoon in which the bee eventually develops. The following spring it chews through the cocoon, breaks the mud wall and flies out.
Females are about half the size of males and the smaller cocoons are always closest to the entrance, as females hatch first. The larger cocoons are the males that hatch last. A dead female near the front can mean the dearth of all cocoons, as sometimes the newly hatched bee does not have the strength to chew through several separations.