What is the point of having certain things live on this planet?

I’ve often wondered what is the point in having lets say house flys or even better mosquitos live on this planet? What benifit do mosqitos have? Are they more of a population thinner, seeing how they cause the most death out of any animal in the animal kingdom? I know frogs, birds bats need insects for food and we definately need insects to help pollinate plants and they are just part of the food chain. Would the world collapse if all mosqitos were eradicated off the face of the planet? (as you can see I don’t like them much as they tend to eat me up when I’m outside) There are plenty of other insects for other animals to eat. Also house flys why do we need them or fire ants for that matter…could the world survive without some of these “pesky” bugs?