Studying bark beetles using bark beetle traps and attractants is an established method in forest health research. Comparative methods for field studies are required to develop and evaluate monitoring and attract-and-kill techniques for forest use.
However, special conditions have to be considered for these studies: (1) unknown bark beetle population sizes, and (2) spatially and temporally fluctuating population densities and other population parameters. Absolute numbers of insects captured in different trap types or with different attractants which were set up at great distances or which were not recorded simultaneously are therefore not suitable for comparative studies. We suggest using the so-called Island Method with different trap types or different attractants set up in a circular way (= island) as close as possible but as distant as necessary. This method allows capturing insects out of the same population, while simultaneously avoiding interactions with adjacent traps or attractants. Data analysis and evaluation are discussed with regard to the problem of pseudoreplication.