I've had this problem before.
I bought some muesli from Tesco-Lotus. It's in a plastic, hermetically sealed bag. I put the bag in my kitchen, ready to enjoy this muesi for brekkies next morning.
The next day, I get ready to savour this tasty food. No such luck! Inside the bag are dozens of tiny black ants, feasting on my muesli!
The bag has no holes - it is still hermetically-sealed with air inside.
How da fuk did the ants get inside?