An investigation on the stems of 26 pedunculate oaks in De Kaaistoep (Tilburg, NoordBrabant, The Netherlands) provided us with many data on the biodiversity of Coleoptera.
We used several methods: bands and rings around the tree-stems and pitfalls at the foot
of the oaks. Moreover, we inspected the stems carefully at night during six years, during
two years this was done weekly. This research was started primarily because we were
interested in the biology of Calodromius bifasciatus, a small carabid beetle recently
discovered in The Netherlands. All the methods used not only gave us insight in the
beetle diversity, but also provided us information about the activity during the seasons
of many species. At least 144 species of Coleoptera were noted on the stems. Most of the
species were detected by sight observations at night and fewer with bands and rings,
although the latter methods gave us additional information. Phenology and ecology of
a number of species are discussed and compared with the literature. Some published
ecological data seem to be incomplete or inaccurate, because they are based on inadequate
research methods. Almost all Coleoptera on trees hide during daytime and are active only
during the night. Therefore their behaviour should be observed during their activity period,
at night, even in winter. It is obvious that some species which currently are referred to as
corticolous are in fact arboricolous, thus dwelling on the trunks instead of under bark.
Some species are active in the winter, amongst others Calodromius bifasciatus, C. spilotus,
Dromius quadrimaculatus and Phloiophilus edwardsii, while entomologists are not used to
study insects outside during that season. Some species believed to be scarce are rather
abundant in the winter at night.
Two species of Dermestidae (not identified) were found underneath the bands around tree-stems of oak trees.