This is an allusion to a German children's song about the cockchafer beetle:
Dein Vater ist im Krieg
Deine Mutter ist in Pommerland
Pommerland ist abgebrannt
Your father is at war
Your mother is in Pomerania
Pomerania is burned to the ground
This song dates back to the early-17th century, when the region of Pomerania was pillaged in the Thirty Years' War. It was commonly sung by children in Germany during the Second World War as the Russian army invaded Germany.