Nigel Brown’s understandable joy in finding a rosy footman in his moth trap (Country diary, 25 August) ends with “an important ecological message” that the substantial elimination of airborne sulphur dioxide pollution, which was devastating to the lichens and algae on which caterpillars of footman moths largely feed, has allowed recovery and even geographical spread.

However, what might be a more realistic message is that the balance has changed in our major airborne pollutants since the 1990s, from sulphur dioxide to nitrogen oxides (a byproduct of internal combustion engines, among others), and this has benefited lichens and algae, which thrive under the current regime – and hence also footman moths as a special case.

But environmental pollution from a host of sources is undoubtedly contributing in an ever more disastrous way to the widespread and massive declines in the numbers of most groups of moths and indeed other insects in today’s Britain. It’s OK for footman moths, but they are not a good model.
Mark R Shaw
Edinburgh