A little inexpensive tip I learned a few years ago at a motorcycle rally in Virginia...
Get a spray bottle and fill it 2/3rds full of water and 1/3rd with ordinary hydrogen peroxide (from the drugstore or supermarket) and spray that heavy on a bugged up windshield and let is sit for a few minutes and wipe it off. The bugs (dried on or otherwise) come right off.
I was told the peroxide attacks and liquifies (excuse my spelling), the bug's skeletons and allows you to remove them easily..
I'm no scientific whiz...but...
It works, I use it all tie time. No dried on, wind blown, sun baked bug can stand up to it.