Due to the unfavourable weather forecast, we had to change the date of the excursion at the last minute. Nevertheless, a number of children and adults interested in butterflies and other invertebrates arrived. With great enthusiasm, they started to hunt butterflies with nets, and collected individuals were identified by experts and supplemented with interesting facts about the species biology. We made a short talk about our projects for adults, and some of them joined the marking of rock graylings after the official end of the excursion. Secrets of the butterfly developmental cycle were introduced to children, using real animals (we observed pupation). The bravest then took the living caterpillars at home for feeding and observation.