Annex door ways

Hi, can anyone tell me the best and easiest way to keep flies and mosquitos out of your caravan annex without having to zip/unzip the canvas door each time. I know it sounds lazy but with 3 young kids always going in and out it would be a whole lot easier to keep the door rolled up but the there's the issue of the flies and mosquitos coming into the annex. I thought of buying the beaded door curtains but do not know if that would work or how I would go about fixing it into place. Would love to hear your thoughts, tips and ideas.
Thanks