Increasing evidence for insect biodiversity decline requires an identification of the causes but also an improved understanding of the limitations of the various underlying sampling methods. Trap comparisons foster comparability of larger-scale biodiversity studies by providing a deeper understanding of the variations in species abundances and trait compositions due to variations in trap characteristics. In our study, we compared five Malaise trap types on their catchability of butterfly species and noctuid moths and examined for the butterflies how this can be related to traits. We showed marked differences in species and trait occurrence in the samples of the different trap types which seemed to be influenced by roof colour (white, black) and trap shape (Townes trap: high, wide roof, Bartak trap: low, narrow roof). We found most butterfly species and most butterfly biomass in the white-roofed Townes trap. All butterfly traits were represented with most individuals in this trap. Compared with its black counterpart, it showed increased catches for pale butterflies and forest species. We found that dark-roofed traps captured fewer butterfly species and had a lower butterfly biomass. Townes traps captured more butterflies with larger wingspans, egg-laying locations higher above ground, and tree feeding behaviour compared to Bartak traps. Depending on the season and habitat, the differences in species capture may affect overall insect biomass.

1. Among the many concerns for biodiversity in the Anthropocene, recent reports of flying insect loss are particularly alarming, given their importance as pollinators, pest control agents, and as a food source. Few insect monitoring programmes cover the large spatial scales required to provide more generalizable estimates of insect responses to global change drivers. 2. We ask how climate and surrounding habitat affect flying insect biomass using data from the first year of a new monitoring network at 84 locations across Germany comprising a spatial gradient of land cover types from protected to urban and crop areas. 3. Flying insect biomass increased linearly with temperature across Germany. However, the effect of temperature on flying insect biomass flipped to negative in the hot months of June and July when local temperatures most exceeded long-term averages. 4. Land cover explained little variation in insect biomass, but biomass was lowest in forests. Grasslands, pastures, and orchards harboured the highest insect biomass. The date of peak biomass was primarily driven by surrounding land cover, with grasslands especially having earlier insect biomass phenologies. 5. Standardised, large-scale monitoring provides key insights into the underlying processes of insect decline and is pivotal for the development of climate-adapted strategies to promote insect diversity. In a temperate climate region, we find that the positive effects of temperature on flying insect biomass diminish in a German summer at locations where temperatures most exceeded long-term averages. Our results highlight the importance of local adaptation in climate change-driven impacts on insect communities.