Adventurepdx's girlfriend here. The one the mosquitoes will follow for several miles in order to feast upon. They will fly past my boyfriend to eat me instead. I dunno if I just taste better or what.
The only thing that works is DEET. But yes, it melts and/or destroys some synthetic fabrics, so do a little research, as I forget which melt and which are okay. (If you're into the technical wool thing--wool is unaffected by DEET.) We used aerosol cans and just took turns spraying each other down with our arms out holding our breath.
And yes, definitely attracted to darker colors. I ended up buying inexpensive thin gray pants (intended for jogging) from MEC in Calgary to wear over my (black) bike shorts after the day we rode into Calgary and I got a dozen mosquito bites on my ass cheeks. Try having that itch in public. Ahahahaha.
Speaking of itching (as you'll inevitably get some bites): you can buy products with names like "itch eraser" that have diluted ammonia in them, and they were the only thing I found that worked on the itching (other than hot showers and ice cubes, which aren't always plentiful while touring). The year of our tour, instead of the usual bites that itch for a couple of days (and stop itching if you press the edge of your thumbnail into the bite), I got a lot of bites that swelled up slightly and itched for over a week. The ammonia stuff stings (and smells bad at first) but it kept the bites from itching for several hours. Benadryl helped too, but mostly by sedating me, I'd guess. I only took it at night 'cause it made me so sleepy.
Oh, and according to the "research" of us and a friend who toured the same summer we did: 9 or 10 mph (assuming no headwind or tailwind) is the speed at which you can outrun mosquitoes. Sounds like no big deal, until you're climbing a hill. Or you have a tailwind as fast as you are.
(Marias Pass, for us, was definitely the worst. CLOUDS OF THEM. They flew in my nose, into my ear, into my mouth. They flew into the holes of my helmet and bit me through my hat. I had to push my helmet mirror out of view or I could see the little cloud just behind me. It was BAD.)