Fixed genus group weights gave a larger trend in adult grasshopper share at six Konza watersheds in 1997–2020

We tested how genus mix affects the fraction of adults in late-summer grasshopper catches. We used 576 equal-effort samples from six fixed, ungrazed Konza Prairie watersheds in 1997–2020. The stage table had 35,721 included insects. The observed adult-share trend was +2.76 percentage points per decade, with a 95% four-year residual-block interval of −1.87 to +7.50. With fixed weights for three large genera and a remaining-genera group, the trend was +6.69 points per decade (+4.26 to +9.18). The direct slope increase was +3.93 points per decade (+0.95 to +6.93). An exact split of the 2015–2020 minus 1997–2002 difference gave −5.48 points from group mix and +12.63 points from changes within groups. Orphulella supplied most of the negative mix part. Eight groups, separate visits, other block lengths, and removal of 2013 gave similar results. One watershed-removal interval included zero. Mean sample day moved later by 5.73 days per decade. The result concerns catch proportions. It does not measure maturation rates or refute a prior study with a different stage score and longer period. We preserve unchanged source files, a count-table audit, code, all draws, figures, provenance, and offline repeat instructions. A separate-folder run reproduced all result and figure hashes.

grasshopper · community composition · life stage · adult fraction · Konza Prairie · phenology · sampling date · reproducible analysis