The use of observation tubes of pure acrylic is not biologically meaningful. Due to lack of gas exchange and the formation of condensation the bee brood falls sooner or later molds victim who grow through the entire pollen nectar mixture and bring the larva to die. This may work one or two summers, but eventually all the tubes are filled with brown discolored, dead brood. The same principle used the nest box monitoring the company Schwegler poking repeatedly to massive criticism among experts. Instead of wild bees protecting one acquires here a Wildbienenmausoleum