Becoming obsessed with a tiny detail in the landscape – the hoverfly – has given Sjöberg a broader perspective than many naturalists. “You realise there’s a lot of habitats disappearing, even on this island, but it’s not as easy as you think to destroy nature.” To take one example, there are no farms left on Runmarö (such smallholdings are not “economic”) and its flower-rich meadows are turning to forest. This is bad for sun-loving species such as butterflies, but Sjöberg points out it will benefit hundreds more wildwood-loving species of beetle….

Optimism, feels Sjöberg, is not the easy option. “Optimism takes time and deep knowledge. If you know a lot about flies you have at least one area where you can read nature and realise it’s not a dystopian novel you are reading.” Optimism is also more constructive. “If the prognosis is too gloomy, you just don’t want to think about it,” he says. “If you want to save the world, the best thing is to create some sensitivity towards nature and the joy of it. You cannot go on about CO2 all the time. No one can be angry or afraid forever. If you want to change the world, you have to build it on some kind of joy.”