The Disappearance of Butterflies. Josef H. Reichholf

a dozen other insect species too. A purple emperor flew towards us out of the wood. When the light caught its wings at the right angle, they seemed to light up, like those of the much larger, more azure, morpho butterflies from the tropical rainforests in Central and South America. It was therefore a male, and, as we saw when it briefly rested on the house wall, of the lesser purple emperor species (see Photo 8). It swung in elegant arcs past the gold and brown immortelle flowers as if carrying out test flights, looped the loop around the petunias, whose flowers in their abundance of bright colours hung from the window sills and from the balcony of the house, putting on a show worthy of a picture postcard, and flew behind the house only to reappear again immediately. It flitted around, here and there, this way and that, for nearly five minutes, and then floated past the balcony and disappeared from sight, until we discovered the object of its desire. It was not any particular flowers or a sunny spot with just the right temperature. It was the cat litter tray. It was not easy to locate this, since there was barely any wind that morning. But the butterfly found it, with its erratic and almost chaotic style of flying, and was finally able to enjoy the excrement of the cat, which slunk around the table by our feet and watched the moths with us, as we checked the catch from the previous night.

What do these anecdotes have to do with the disappearance of the butterflies? Purple emperors are, if I may be permitted the expression, glimmers of hope. They still exist, and indeed, as I would like to emphasize, in greater, not smaller numbers than in the forests of my earlier research activities. Taking into account the fact that I have visited the riparian woods and commercial woodland of southeast Bavaria significantly more often since my retirement, because June and July were always term-time at the universities of Munich, and I cannot keep away from the purple emperors on a favourable day, I would tend to say that their population was ‘unchanged’. This is a helpful finding, since one must clarify which butterflies and moths in which habitat types have become scarcer in order to discover the causes. For this reason, we will now turn our attention to the Lepidoptera of the nettle patch, which have a few things in common, not least that nettles are the principal host plants for their caterpillars. Our considerations will be focused on the caterpillars and their requirements rather than on the butterflies themselves.