I think it is sad but ethically acceptable to kill an ant colony in my house, yet I don't think it is OK for children to go in the forest and destroy ant colonies for fun. Or even to dismember one ant for fun, though I may be in a small minority here.
To take a more extreme example, a majority of people seem to find it ethical to have drone strikes in Pakistan despite the civilian casualties. They would certainly not approve of the same drone strikes if they were made for entertainment, even though the physical consequences on the targets would be the same.