I am addressing this issue with my J160. It spent a few years outside on the handstand, with a pumpkin head cover, at least. The wings, tailplane, etc., were not covered by the pumpkin head cover; they were powdery to the touch and felt rough. The bugs take time to clean off after flight.
Over the last few days, I have been cleaning and cutting with Septone Cut and Prepare (Step 1) and following up with Septone Polish and Protect (Step 2). The areas I have done so far feel smooth and clean; the bug guts wipe off with a little spray cleaner, and water easily beads and runs off.
Being a wax, it can be removed for repairs when needed. I did a day of work by hand but struggled to use my arms the next day, so I upgraded to an 18v battery polishing/buffer machine, which is perfect. Once I have done the whole airframe (excluding windows), this will be an every 6 months maintenance task for me, especially as she sits in a hangar now and is no longer exposed to the elements, except when she flies.