Several solitary bee and wasp species accept glasstubes as nesting place. Of these Osmia rufa and Heriades truncorum are the most common species. Glass tubes were taken out of the nest-box after the opening was closed. Mould appeared a major problem in these tubes. Nevertheless, some interesting observations could be done. A Symmorphus species, probably S. connexus, occupied tubes with a diameter of 3 mm. Eggs were seen on the first Chrysomelid larva collected. The number of larvae depended on their size. This species appeared to have a second generation. Development time of specimen of the first generation lasted about one month. Their pupae are yellow and naked. Two specimen were eaten by the ectoparasite Anthrax anthrax. The larva of this parasite did not attack until the wasp larvae had pupated. Hylaeus signatus larvae were infested by Melittobia acasta. This parasite spread to the other glass-tubes. Also an A. anthrax pupa was eaten. M. acasta produced a few males and a lot of females with a slender thorax. In two lots there existed only females, in this case with a robust thorax. Both types were fully winged. On spiders collected by the sphecid Trypoxylon figulus were larvae of probably a beetle species. These larvae were eaten by the T. figulus larvae together with the spiders.