here's a bit of advice from the bmw motorcycle side of things...


get an old towel or rag and soak it through with water and allow it to sit on the offending bug mess for an hour or two (it really doesn't take that long); keep wetting the towel to make sure it stays wet.

through simple osmosis/diffusion, the water will rehydrate the dried bug parts to slimy, and then simply wipe, wash, etc. off softly. no problems... that's how we clean our motorcycle helmets when travelling and stopping overnight. also cleans the bike that way, but it seems to upset the motel/hotel management when we come back in with a bunch of dirty towels...