Body size of terrestrial arthropods and biomass of their populations in relation to the abiotic parameters of their milieu.

From collections made in very different biotopes of very different zoogeographical regions it is concluded that the biomass per area, the average body size, and the number of winged insects and spiders are primarily governed by the relative humidity of the biotope. From this finding several predictions are put forward on parental care, social systems, activity time and predators in different biotopes all of which seem to support the hypothesis.