The variance of annual moth catch changes was above a zero-covariance reference at 11 Finnish traps, 1993–2019

We tested shared annual changes in moth catches at long-running Finnish light traps. We used source records from 1993–2019 and fixed seasonal coverage rules. The sample had 11 locations, 228 trap-years and 191 changes between consecutive years. At each trap, we divided total catch-change variance by the sum of species change variances. The denominator is the reference variance when species covariances are zero. All trap ratios were above one. Their geometric mean was 5.46, with a nominal 95% joint block interval of 3.70–8.02. Removing the largest-catch species at each trap gave 6.09. Removing five cyclic species gave 5.71. A stricter coverage check retained only four traps. The result shows positive net covariance in recorded catches. It cannot separate population change from shared weather effects on flight activity and capture. The selected records do not represent all Finnish moth populations. The package preserves the unchanged source archive, code, selection records, results, figures and offline repeat instructions.

moths · species covariance · light traps · Finland · community stability · sampling effort · reproducibility