Open Jersey Riding

My morning bike commute starts out with a few miles of either flat riding, or gentle slope downhill. Then it turns uphill on its way to Reston. Once in Reston, the last 1/4 or 1/5 of the trip is pretty flat again. When I leave my place, I'm not warmed up yet, and since it's still spring like temps (50's-60's) I'm quite comfortable. But by the time I start the uphill climb, my body is warmed up from the 3 or 4 miles I've just ridden. And I'm not exactly light, so I have to work harder to go uphill, so I start to warm up. I usually unzip my jersey a little to get some circulation on my chest. Well, that's all well and good until a multi-legged and winged creature gets caught in my jersey. Granted, it's not their fault. They're just happily buzzing along their merry way when all of a sudden this fat cyclist comes by doing 17 MPH and WHACK!!! they're caught inside my jersey. Now since my skin isn't hard like a windshield and I'm not going 35-55 MPH like a car, this impact isn't enough to kill them. So now I've got his highly upset creature inside of my jeresy. And what do these types of creatures do when upset or feel threatened? They sting or bite, of course. So I've got a nice welt just below my right shoulder today.