The European Butterfly Monitoring Scheme (eBMS) is a joint initiative of Butterfly Conservation Europe and the Centre for Ecology & Hydrology. It is a home for promoting butterfly monitoring schemes across Europe and consists of the following activities:
The EU Butterfly Indicator for Grassland species, 1990-2017, has a dedicated technical report to describe the indicator. It represents a major update on previous versions, through the incorporation of more and expanded datasets, together with new analysis techniques. It is the first major output of the Assessing ButterfLies in Europe (ABLE) project. The EU Butterfly Grassland Species 1990-2017 indicator is part of the monitoring report on progress towards the SDGs in an EU context — 2019 edition, which can be accessed here. The grassland butterfly indicator contributes to Goal 15: Life on Land.
You can download the EU Butterfly Indicator for Grassland species: 1990-2017 Technical report here.