My husband has decided to keep a pet caterpillar. It is disconcerting to see it sleeping under his nose as we have a conversation. When we kiss, it wriggles and prickles in discomfort. A top lip is not the best home for a caterpillar. One day, it may move on, find an appropriate place to live, crawl under a damp cabbage leaf. Or perhaps it will spin itself a silky cocoon, grow beautiful wings and flutter away.