Why oh why do giant apes, insects, arachnids, have this overwhelming desire to trash iconic buildings and bridges? Thoughs on 'z' grade movies. -- Knitnan
It woke. It felt strange. Different. In pain. Angry. These little things that once were larger were the source of its pain. It knew this. Instinctively.
It had more brains to think with. Some things merely scaled up, but others... scaled exponentially. More neurons meant more connections. More connections meant greater learning. Greater learning lead to a normally small creature thinking things that a creature of its kind was never meant to think. And it quickly came to the realisation that it should never have conscious thought in the first place.
So of course it got angry. It wanted to harm the creatures that made it this way. Going after individuals took far too long. It had a concept of passing time now. An awareness of its own mortality. Somehow, it knew how long it had to live, which was drastically shorter if it just started eating the humans willy-nilly.