Hi! I apologize if this has been covered but I could not see a way to search just this post for the terms I was looking for.
One thing that came to mind that I did not see covered was what did Mike O. do to prevent termites?
I saw the post about using a certain grit sand and also thought that in some manner DE if it could be put in the right places would be a good deterrent.
Lastly when I lived in Fl and was researching this I was led to spraying a Borate solution
http://www.life123.com/question/What-Is-Borate on every piece of dry lumber before it was installed. Borate is used as a food additive in some countries and is safe it seems. Also boric acid from my experience is the best thing in the world to kill roaches.
I hope I have given you a starting point as I am hoping to benefit from this discussion also and build a small shelter myself here in a few months.
Blessings
Joe in Missouri