Cockchafer

It rained! Soft, warm, glorious rain that made the earth smell sweet and intensified the perfume of all the flowers.The garden breathed a sigh of relief. So did I, as it meant a day off fieldwork and some time to catch up with other tasks, particularly preparing for three days teaching in Leeds next week.

We ran the moth trap last night and captured the first peppered moth of the season (see extra), and this magnificent cockchafer, which we now see every year. Cockchafers were once highly abundant until pesticide use in the mid 20th Century almost obliterated them. Thankfully they have been making a come-back since the 1980’s with the regulation of pesticides. We never captured them in the garden during the 1990's, and it's only in the past decade that they've become a regular feature of the moth trap. 


Peppered moths are well known by biology students as one of the clearest and most easily understood examples of Darwinian evolution in action. Before the industrial revolution in Britain, most peppered moths were of the pale variety, like the one we caught. This meant that they were camouflaged against the light-coloured lichen covered tree bark that they normally rest on. Moths with a mutant black colouration were easily spotted and eaten by birds. This gave the pale variety an advantage, and they were more likely to survive to reproduce.

In the late nineteenth century airborne pollution in industrial areas killed lichens and blackened tree bark with soot. This meant that the mutant black moths were now camouflaged, while the white variety became more vulnerable to predators. This gave the black variety an advantage, and they were more likely to survive and reproduce. Over time, the black peppered moths became far more numerous in urban areas than the pale variety. With cleaner air, and a resurgence in lichen growth on trees, this situation has now reversed and the pale varieties are generally more dominant even in industrial areas.