Last year I was lucky enough to photograph a female Large Blue Maculinea arion (l'Azuré du serpolet in French) egg laying on the Wild Oregano Origanum vulgare in the field opposite our orchard.
This species is one of a number of butterflies referred to by ecologists as 'Grassland Indicator Species'. Their abundance helps scientists determine the ecological health of natural grasslands. The bad news is that their population declined by 50% between 1990 and 2007. The good(ish) news is that the warning bells were heeded, at least for this species, and the situation may have been improved (although the longterm trend is still uncertain).