Nature sure has a funny way and is yet a well "oiled" eco system - I know, the irony - in keeping itself sustained. This was called the "circle of life" in the animated movie The Lion King. It's also a lesson I've learned in biology class: the bug eats the plant, bug gets consumed by a bird, which is then food for a snake and in some cases the snake becomes the meal of a honey badger (I've just seen a scene from a documentary in how predatory those mammals can get). The honey badger will then after some time, be broken up by microorganisms into nutrients for plant life. Hence, the cycle starts again.
Whenever I see bugs on flowers or plants, I get reminded of that part of life and I also realize that too much of an organism without natural predators may become catastrophic. Like too many ant colonies in a forest, breaking up all the greenery and in some cases may even destroy a forest. Of course that's a worst case scenario and ants or bugs serve other functions, but the balance should be kept, without too much outside interference.