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Abstract Annual insect abundances are determined by short‐term population fluctuations and long‐term trends in community composition. Any assessment of this temporal variability needs long‐term quantitative data on abundances. Here we use museum data (1940–2017) of butterflies and burnet moths from southwestern Germany and central Austria comprising 220,758 records from 155 species, and 55,641 records from 170 species, respectively. We ask whether population fluctuations and long‐term population trends are spatially synchronized across larger spatial distances (>300 km) according to the Moran effect, and whether common trends in community composition and stability exist? Population fluctuations of 85.5% of species jointly occurring in both study regions were positively correlated (mean r = 0.30 ± 0.03). Comparing different time windows, we found different sets of species being in spatial synchrony reflecting temporal changes in butterfly community composition. Mesophilic, habitat generalist, and dispersive species were significantly more synchronized than xerothermophilic, habitat specialist, and sedentary species. Long‐distance travelers were particularly synchronized. In both study regions, species rank orders became less even with time. Stability in community composition increased with time with an ongoing trend to faunal homogenization, but not to species loss. Our study points to global and not to local drivers behind trends in butterfly population fluctuations and compositional stability, in the present case to altered land use and urbanization as major drivers toward synchrony and homogenization. Finally, our data have implications for conservation strategies as they strongly indicate that natural landscape structures are associated with higher faunal compositional variability in comparison to agricultural and urban landscapes.

This paper presents a revision of the genus Dyscia Hübner, [1825] (Lepidoptera, Geometridae: Ennominae). Examination of types and additional material for most described taxa has resulted in several new synonyms: Dyscia ilivolans Wehrli, 1953 syn. n. and Dyscia duanjiao Yang, 1978 syn. n. are new synonyms of Dyscia fagaria (Thunberg, 1784); Dyscia karsholti Wiltshire, 1991 syn. n. is a new synonym of Dyscia galactaria Turati, 1934; Dyscia dagestana Wehrli, 1934 syn. n. is a new synonym of Dyscia malatyana Wehrli, 1934, and Dyscia rjabovi Wardikjan, 1957 syn. n. is a new synonym of Dyscia negrama Wehrli, 1953. One taxon, formerly treated as a species is reassigned to subspecific level, Dyscia conspersaria ssp. sultanica Wehrli, 1936 stat. rev. Dyscia innocentaria sicanaria (Oberthür, 1923) stat. n. and Dyscia malatyana senecai Wiltshire, 1990 stat. n. are downgraded to subspecies-level. On subspecies-level, Dyscia distinctaria perdistincta Herbulot, 1957 syn. n. is a new synonym of Dyscia distinctaria (Bang-Haas, 1910), Dyscia fagaria alvarensis Wahlgren, 1913 syn. n., Dyscia fagaria albescens Lempke, 1952 syn. n., Dyscia fagaria fusca Lempke, 1952 syn. n., and Dyscia fagaria postdelineata Lempke, 1952 syn. n. are new synonyms of Dyscia fagaria. Dyscia fagaria psoricaria (Eversmann, 1848) syn. n. is a new synonym of Dyscia fagaria favillacearia (Hübner, [1799]), Dyscia holli duponti Thierry-Mieg, 1910 syn. n. is a new synonym of Dyscia holli (Oberthür, 1910), Dyscia malatyana nachadira Brandt, 1941 syn. n. and Dyscia malatyana theodoraria Warnecke, 1941 syn. n. are new synonyms of Dyscia malatyana albersaria Warnecke, 1940 stat. n., and Dyscia penulataria naevata Wehrli, 1953 syn. n. is a new synonym of Dyscia penulataria (Hübner, [1819]). Lectotypes for 22 taxa and neotypes for three taxa - Geometra conspersaria [Denis & Schiffermüller], 1775, Geometra favillacearia Hübner, [1799], and Geometra emucidaria Hübner, [1813] - are designated. One species is excluded from Dyscia, Thysanopyga serena (Dognin, 1906) comb. n. From a total of 72 previously described taxa, 19 are recognized as species.