The Finnish rule "Live and let others live!" means roughly that "it is ok to be selfish (in ways positive for happy life) but not to disturb the lives of others, not to cause unfairly harm to others".
So if there for example is a meadow full of insects and they eat lots of other insects and birds too eat them, one could still use this rule:
Just avoid things like torture and ruining the society and instead preferably make murders, possibly with cannibalism but with the consequences of each murder and especially of many murders and decisions to not to murder someone, taken into account morally, wishing for the good of the society and of the world in the long run..
That is just why we have armies and police, even education: to prevent worse, even if it means killing many. That is just how societies work well, protect good life by common effort. If some insect eats the corpse, I do not see how it would somehow be wrong in essence, it sounds like natural, but of course if one makes it a habit to kill without regard on whom one kills and why, just kill somebody when one is hungry, does one then kill the friendly morally ok society members while enemies of the society keep distance and that is wrong, just against the idea, against the right to kill someone, namely the enemies of good life should be killed and those creating good life in the society and in the world should be given well room to live in and safety & fair support.