Mr. Clean Magic Eraser. Make it wet, but not dripping. Simply wipe a small area, and follow with a soft dry cloth or towel. Everything melts off. Yea, it takes a little effort, you may even have to use a step ladder. But the chemicals in the Mr. Clean Magic Eraser will not hurt the awning, and they will also leave a chemical that will help retard black mold growth. It won't help for bugs that die or may get rolled up, but a little touch up every now and then and it will stay white and pretty all the time.
The secret is NOT to rub the eraser, simply wipe while it is good and wet. Dip in water again when it get's a little dry and keep repeating. If the dirt does not come off right away (but it will), simply go over the area a second time and follow with a dry cloth. The dry cloth will take off the dirt. So it's OK to rub the cloth to dry the awning. Do it in small 2 foot square sections and you'll get it done. It takes me about 30 minutes to do my awning.
To do the top, I use a long painter's handle with a soft brush on the end. I then wrap it with a wet towel and simply put the eraser between the awning and brush wrapped with the towel. The weight of the towel will be just enough for the eraser and the towel will remove the dirt. Simply move the painters handle back and fort until the entire upper side is clean.
My first 2 campers had a manual awning, and I was able to lower the arms completely and slide them under the camper, allowing the awning to hang completely down on the side of the camper. Then I used the Mr. Clean like cleaning a flat side. Simple wipe and follow with a soft cloth.
The good thing about this is, it keeps mold and icky black stuff from coming back for a long time.