For the former (German study with the biomass numbers), perhaps? For the review study (which reported on worldwide species numbers and Britain range distributions), I flipped through the supplement and it looks like they actually did try very hard to adjust for the fact that they were working off of volunteer data (Filtered for surveys that had identified certain other similar species, and which had lasted for over 1hr. Also, excluded some species that they expected to have “gone into hiding” more). Something interesting might be going on with the Beetles, but it seemed suggest that Butterfly/Moth and Wasp/Bee/Ant species are almost all either holding steady, or dropping. I think significant reductions in flying insect catches might actually be plausible.
For the former (German study with the biomass numbers), perhaps? For the review study (which reported on worldwide species numbers and Britain range distributions), I flipped through the supplement and it looks like they actually did try very hard to adjust for the fact that they were working off of volunteer data (Filtered for surveys that had identified certain other similar species, and which had lasted for over 1hr. Also, excluded some species that they expected to have “gone into hiding” more). Something interesting might be going on with the Beetles, but it seemed suggest that Butterfly/Moth and Wasp/Bee/Ant species are almost all either holding steady, or dropping. I think significant reductions in flying insect catches might actually be plausible.