What kind of bugs? You will need to be a bit more forthcoming with details and/or photos to get very pertinent advice about removal or control.

Mosquitos or flies I presume? I don’t have any actual photos of the bugs- I just know that when we sit out there I can feel the bugs biting.

Sounds like you need a fogger. It will clear out mosquitoes for about 3 days. But also need to check below deck for standing water. Even if there isn't any, mosquitoes go to cool, dark places to wait out the day. It looks like a grade level deck from this one picture. Is there access from the other side?

@Yardvaark no access from the other side either. I can’t get under it at all. 🤔

I didn't mean for you to get under the deck. Just look with a flashlight. Is the ground below the deck sloping substantially in any direction?

The fogger will work whether you can see under the deck, or not.

I would be highly skeptical that the habitat beneath your deck is a major source of flying insects pestering you while deck lounging. That said, there are any number of broad spectrum bug poisons you can get at the Big Box to spray or sprinkle as granules between the deck boards to see if that makes any improvement.

There is a reason for screened porches and patios and some people are just bug magnets.

My sister-in-law had a deck very similar to this at her house in Oklahoma. She complained about bugs including centipedes, millipedes, etc etc so this spring they ripped it off and installed a large concrete patio in its place. I thought that was a silly waste of $$$ - unless you screen it all in, there’s going to be bugs! It’s the outdoors, people.