I've found another Thread
that mentions mosquitoes in other Jayco units.
Our family upgraded from tenting and moved into the line of luxury offered in a brand-new off-the-lot 2013 154BH. We were camping near Lake Superior and the mosquitoes were bad. When we woke up they were worse. My wife suspected they were coming in through the Microwave kitchen area. I suspected it was the Air Conditioner (which gives passage way to the Microwave).
The side mounted AC unit draws outside fresh air from the roof, and blows the heat out the side. The side looked impermeable. So I climbed on the roof. With a little bit of prying under the white cover, I could feel a screen of sorts. So I removed the 4 screws and the white cover. I've attached a picture of what's underneath.
That's only keeping out rabbits. So the big mosquitoes are on a weight-loss program so that they can invade our trailer through the AC unit.
I purchased a mosquito parka and duct-taped it to the vent and put the white cover back on. Ahh, bliss.
Besides the bugs. Maybe I should mention how the new camping experience was. We pulled the trailer with a 2002 Dodge Caravan SE. 3.3 liter engine. Weight-distribution hitch with friction bar for anti-sway. Pulled for 3000kms like a dream. The van has an extra transmission cooler and a transmission temperature gauge (cheap digital voltage meter that came with a thermocouple which I tied to the dip-stick). The hottest it got was 200F and that was not in the hills of Superior. It was in the plains of Manitoba with a brisk wind coming at us but 45deg off (not directly). Overall trip mileage: 60mph cost 15mpg.