The Meetnetten - Transects for butterflies in Flanders, Belgium dataset is a sampling event dataset published by the Research Institute of Nature and Forest (INBO). It is part of the Meetnetten.be suite of monitoring networks for priority species in Flanders, in which data are collected at fixed locations using a standardized protocol (https://meetnetten.be). This dataset contains transect data for 8 priority butterfly species, as well as other butterflies observed during sampling. Here it is published as a standardized Darwin Core Archive and includes for each sampling event an eventID, date, location and sampling protocol (in the event core), the cloudiness, temperature, and wind force at the time of the event (in the measurement or fact extension) and for each occurrence an occurrenceID, the number of recorded individuals, status (present/absent) and scientific name (in the occurrence extension). Issues with the dataset can be reported at https://github.com/inbo/meetnetten-occurrences/issues Generalized and/or withheld information: as these are sensitive priority species, location information is generalized to 1, 5 or 10 km Universal Transverse Mercator (UTM) grid cells. Original locations are available upon request. We have released this dataset to the public domain under a Creative Commons Zero waiver. We would appreciate it if you follow the INBO norms for data use (https://www.inbo.be/en/norms-data-use) when using the data. If you have any questions regarding this dataset, don't hesitate to contact us via the contact information provided in the metadata or via opendata@inbo.be. For all published Meetnetten.be datasets, see https://www.gbif.org/dataset/search?project_id=meetnetten.be