The short answer to your question is that it depends.  It depends on how the language of the insurance application is worded.  If it refers to arrests, then you definitely have to disclose it.  If, however, it only refers to convictions, and you are absolutely certain that any criminal charges that you once had ultimately resulted in dismissal, then you probably do not have to disclose it.  A dismissal is NOT a conviction.  However, you should be very careful that you do not misrepresent anything, due to the fact that any misrepresentations on an insurance application could cause it to be void later on down the road.  Therefore, if you are uncertain about any of the language you should consult with a local attorney to discuss this matter in greater detail.