I remember in the mid seventies we had huge swarms of ladybirds here in Hull. There were so many that the pavements were red and we couldn't walk without crushing hundreds of them. My mother had the screaming ab-dabs as she had a pink sheet on the washing line and it was covered in ladybirds!
They were still building the Humber Bridge at the time and they had to stop work on the towers due to the swarms. I seem to recall they followed an equally large swarm of greenflies..everyone was walking around with scarves round their faces to avoid breathing them in. I think it was around 1976 which had been an exceptionally hot summer.