Where in Germany is that? In Dresden I saw flies even on warm days in February.
I don't track insects all that much. We seem to be OK at least as far as numbers are concerned - plenty of bees, flies, mosquitoes... This is just a totally amateurish assessment on my part, though - as I am certainly an opposite of an expert when it comes to this topic.
RE: 31 August 2019 - Bees working flowers