They really need to read the book instead of relying on that cartoon of a movie.

Humans and the bugs were expanding into the same section of the galaxy and the bugs (or their hive mind) decided they didn't like the competition and started opening wormholes and throwing rocks at earth. They knew about humans before humans even had an inkling sentient bugs existed.

So humans only started punching back after sneak attacks on already established human colonies.

They really need to read the book instead of relying on that cartoon of a movie.

Humans and the bugs were expanding into the same section of the galaxy and the bugs (or their hive mind) decided they didn't like the competition and started opening wormholes and throwing rocks at earth. They knew about humans before humans even had an inkling sentient bugs existed.

As well as sneak attacking already established human colonies.