I've noticed a few people have gotten stuck on level 2, so I'll try and explain the mechanics and solution if anyone else gets stuck. So do look below if you fell stuck on that level.
In order to get past the wall, you need an attack, similar to the insect's attacks on level 1. The level contains a kind of lemon-yellow insect with a circle around it, and any entity that is that colour will turn anything touching the circle around it into the same type of creature (in this case the insects), which can give you the attack ability to break the wall blocking the flag.