It just goes to show that all creatures have a purpose.
Your comment Neil, brings two thoughts to mind.
1. Actually, wax moths are beneficial in their destruction of honey comb---when it comes to unattended hives that have been killed off by disease. If those combs were to stick around, they would serve as a long term source of infection for countless hives. Unquestionably, wax moths were a factor that helped keep bees alive before man got involved and decided to help keep bees alive. I'm sure theere are other benefits they provide, we just have to think about them the right way.
2. As a child, I remember one of my favorite bed time stories, about yet-to-become-king David. He had shown disgust of spiders and felt they were worthless animals. God taught him a lesson: When he was being chased by King Saul, who wanted to kill him. David hid in a cave and God sent a spider that spun its' web across the entrance. When King Saul arrived at the cave, he saw the web blocking the entrance and figured that David couldn't have entered the cave without damaging the delicate web. Rather than waste his time searching where he assumed that David couldn't be, he left the cave and went on with his searching elsewhere. The rest of the story is history
Yes, all creatures have a purpose, and when we all understand that, we'll get along better in this world.