Arthur is a caterpillar-in-waiting. He is waiting to become a moth and has built himself a chrysalis in readiness for the day. However this awaited transformation to mothness has been a long time in coming and during this waiting period Arthur has built up a wealth of useless information that he is all too ready to impart to anyone who will listen. He is like a London cab driver - an opinion on every topic. Sadly, for Arthur, he is nowhere near as clever as he thinks he is. Consequently, he is more than happy to 'hang out' with Mavis because she makes him feel superior. He is quite nervous of Evil Edna and avoids crossing her.