- Lafranchis, T. (2009) Dagvlinders van Europa. KNNV Uitgeverij, Zeist.
- All* butterflies are caught with a specific insect net.
- They are tranferred to a petridish, whereafter photographs are taken from the upper and under parts.
- Thereafter, the butterfly is released.
- Photo’s are stored in a database.
- Observations are uploaded to NAFI at Laij.fi
- Figure 1 shows the relationship between the number of excursion days and the number of species observed per year.
* Of easy reckognizable species (e.g. L. virguareae, A. hyperanthus, etc) only a few individuals are caught and photographed.
Figure 1. Relationship between the number of excursion days and the total number of butterfly species observed per year. When <6 excursions, species numbers might be underestimated. The years 2005 and 2014 seem to have had relatively low numbers of species.