So far, I've refrained from using tarp shelters in heavy mosquito country. I have a Go-Lite Hex which seems like it might be effective vs bugs with door shut. Can anybody offer an informed opinion about the effectiveness of this type of shelter without netting regarding insect protection? I'm not particularly interested in the netting accessories.

If you seal it up tight enough to keep bugs out, you're not going to be venting.

It'll turn into a sweatlodge in there!

This is the big tradeoff with bug protection in a shaped tarp: if it's calm enough that the bugs are out, you need your vents working. And if it's windy enough to seal the shelter tight to the ground, there won't be any bugs out!

Some people sew or velcro 1-2' of bug mesh around the bottom of their Hex-type shelter. This allows a "breathable" pitch with decent bug protection.

>>This is the big tradeoff with bug protection in a shaped tarp: if it's calm enough that the bugs are out, you need your vents working. And if it's windy enough to seal the shelter tight to the ground, there won't be any bugs out!

This has also been my experience. Lately, for a number of reasons, I've been gravitating back to my shaped tarp, the silshelter. But in heavy mosquito country, you have to bring some kind of netting. In my case, it's the A16 bug bivy. Tarptents are great when the mosquitoes are heavy, but they tent to let the cold winds in as well.