Today, I came home and saw a caterpillar-like thing lying at the entrance of the building with a white circle on it. What bug is this? Is it poisonous?

The place where I come from is called "Stabbing Mao Feng". It is harmless. But don't touch it, don't go near it, you should clean it at once, if you touch it or get too close, you will itch all over. What trees should be planted near your home? Go and see many trees.