Think about what you live for. While we (in some ways) help the chain of animals live, we mainly live because we have the instinct to do so, and we have emotions to back that up with reason. We squish bugs because they're tiny, pointless, we can't percieve their emotions, and they can't fight back. But they still have the instinct to live, and they probably have something that backs up their will to live for them, whether it be emotions like us, or some other thing.