I know there are some insects or bugs that are beneficial to the ecosystem. They help out in agriculture in one way or another. This doesn't mean all of them are equally that useful.
Which insect do you hate most? Bed bugs is my most hated insects/bug.
Flying roaches. I've dealt with bees, wasps and all sorts of other bugs but flying roaches are the ones I dislike the most due to the fact that I once saw one literally fly into my brother's mouth when we were younger... (I mean it's hilarious but disgusting as well)
For me, it's cockroaches. They are just too nasty. I also hate that they can breed in any place including clean places too. Another one is mosquitoe. Nothing hurts more than to have them bite you and feel the swelling and itching sensation.