Let's move on to the second example, which is a possible sentence: She kills the worms by stepping on them. There is only one action - she steps on the worms. As a result of this, the worms die. We can say, therefore, that she kills the worms. We can also say that the worms cease to live. We could say perhaps that she commits lumbriciciniide. We could perhaps think of several other ways of talking about this brutal act. There is no confusion.