Mesobromions are known to be regional centers of biodiversity and are protected by the Habitats Directive of the European Union. Despite a severe decline in area size, a relatively high density of this habitat can still be found in South Styria. Heteroptera communities of eleven Mesobromions and one species-rich mesic meadow were sampled with a suction sampler. Altogether, 2581 bugs from 105 species were detected. Three species (Tinicephalus hortulanus, Omphalonotus quadriguttatus, Scolopostethus lethierryi) were recorded for the first time in Styria. Differences in incidence and abundance between the sites were high, ranging from 10 to 40 species and 34 to 1042 individuals. At least one of the 22 recorded red list species was found in each site. However, the eight actually endangered species were restricted to five Mesobromions. Intra- and extrapolation of species numbers predicted undetected species for all sites. Outcomes of suction sampling clearly deviated within the sitesthus, the placement of the device played a crucial role and/or the sample size was too small. Mesobromion sites revealed a high heterogeneity with respect to dominance structure, abundance and incidence. Differences between the coenoses were mainly influenced by species and individual numbers, while other parameters seemed to be absent. Exploring ecological traits (ecological types, ecological guilds, habitat requirements) revealed similar effects. True bug densities were higher in pastures (n = 3) than in hayfields (n = 8). Distinct differences between the management types according to ecological traits seemed to be absent, although grass dwellers and partly also edge species were less frequent in pastures. Mesophilous open-land species were more frequent in pastures than in hayfields. Consequently, differences between mown and grazed Mesobromions seemed to be more influenced by quantitative than by qualitative traits. 32 species were identified as character species of Styrian Mesobromions.