The decline of biodiversity in general and of insect diversity in particular has been recognized as a major environmental problem in recent years. The study of Markl et al., in which this dataset was used, reports the distribution and the decline of populations of forester moths of the genus Jordanita in Central Europe since 1950 as a type example of the loss of grassland biodiversity, and discusses the reasons for this decline. Based on extensive work in museums and private collections, a literature review and own observations, and including data as far back as 1834, this genus helps to understand the deeper reasons of insect population and biodiversity decline, as the well investigated six Central European species cover a broad range of extensive grassland habitats (fens to low-production grassland and xerothermic steppes) from low altitudes to high alpine meadows. Therefore, they monitor processes relevant also to other, less investigated grassland species.

This dataset was assembled using various approaches:

1. The available literature on forester moths in Central Europe since 1834 (Boisduval, 1834) was screened in detail to find every locality mentioned (see Efetov & Tarmann, 1999; de Freina & Witt, 2001, for a comprehensive list of references).

2. Many of the most important European museum and private collections on Lepidoptera were visited in the last 55 years and data on forester moths were collected.

3. Extensive field studies and mapping trips as well as exchange of knowledge with many colleagues augmented this database leading to a clear picture of the original distribution of the six investigated Jordanita species in Central Europe, their decline or, respectively, the areas where populations could withstand this trend of decline.

In total, about 15.000 museum specimens were examined, about 500 references were searched and all these data were then implemented into the BioOffice database of the Collection and Research Centre of the Tyrolean State Museum, Ferdinandeum, Hall in Tirol, Austria.

The data are in an Excel file and only Excel is needed to open and use them.