These are traces from insects trapped in the bright flare of a flood light.
Night active insects get attracted to light and are held captive, try to escape but are blinded. So they fly in circles in order to escape, but cannot.
Eventually they either die of exhaustion, or get eaten by predators.
This massive dying every night in every city worldwide has severe effects on the population and on other species up the food chain:
https://phys.org/news/2019-02-world-catastrophic-collapse-insects.html
"Experts estimate that flying insects across Europe have declined 80 percent on average"
#internationaldarkskyweek #insects #foodchain #lightpollution #extinction #nature #light #led #energy
Image taken for illustration from
https://www.freeimages.com/photo/insects-with-light-1179234