Conscious? Yes, though their experiences are undoubtedly quite different from humans’.
Doesn’t that render the world a place of unbelievable suffering? I believe it. I’d say rather a place where an unimaginable amount of different experiences are all happening – some of which are suffering, and others aren’t, at any given time.
Do you suppose bugs themselves capable of suffering? Yes. I am quite certain I’ve observed bugs suffering. They certainly show different types and levels of alert, panic, and are capable of various appropriate responses to different situations, even unnatural situations, such as being moved by a human onto a miniature newly-created island in water.