Sunburst To Cloudburst

Despite all the warnings it hasn't been that hot here today and it rained this afternoon.

I photographed this Muscid fly on a dead twig covered with Xanthoria parietina lichen. Many lichens will not grow in polluted air. The presence of this sunburst, pollution tolerant, lichen points to a higher than normal level of nitrogen pollution. It can be used as a biomonitor of air quality.