Best way to keep the bugs out

Same thing applies with a DH who can open doors but somehow lacks the skill to close it.....you might set a bug candle in a safe place - away from small hands - and keep it lit during the day as well as evening. If it's mostly flies, while not attractive, you could check into fly strips and hang from the awning close to the door. For some time we've been doing battle with Lady Bugs....have about decided they came OEM. Trying to be good to them, gently pick them off the window area and out the door, but giving serious thought to setting off an insect fogger. These babies seem to love the warmth of the window area.

It's almost impossible to keep the flying insects out during the day when people are coming and going. A trick my late wife and I learned when we lived in Somalia, though (mosquitos carrying malaria were the risk there), was to keep a can of pyrethrin insect spray handy. After you're in and the doors are closed, do a quick spray around the top of the walls (where the wall meets the ceiling). The mist will drift down and kill insect on contact. (Also works for mosquito netting tucked in around the bed.) Mosquitos tend to gravitate toward the vertical surfaces and pyrethrins are considered nontoxic to people and pets.

If you have power you could run a fan pointing toward the door causing a breeze to make it harder for the bugs to come in.

Find a way to hang screen outside the door so you have to go through it like a curtain.

Along the lines of the post by tessa25, I think I would try one of those Magic-Mesh screens that were "As Seen On TV" but now available everywhere.
Barney