Why do they always appear when I'm trying to eat? 
Why do they fly round and round in the same spot for ages?
I understand they have their place in the food chain, but apart from that, do they serve any purpose (e.g. pollination, other pest control)?

Why do they fly round and round in the same spot for ages?

I understand they have their place in the food chain, but apart from that, do they serve any purpose (e.g. pollination, other pest control)?

