Hello Michelle. Summer will be a time for lots of insects & depending where you live you may have to get your shop screened. Particularly a sliding screen door. Other than that you could buy your self one of those beaded door hangers that you hang over the door frame. some of them are quite decrotive but you'll find the kids like to constantly walk under them all the time or touch them so that they break easily. Alot of retailers have air conditioning too so that helps reduce flys as flys prefer the heat. But if you cant afford air conditioning you may just have to go with the screens or the beaded door strip. Hope I have helped.
Regards Helen