Invasion of ?

Can anyone help ID these critters who have attacked my plum tree?

Thanks,
Al

 

that's a fabulous pic!!! it's a promethea moth caterpillar.

 

Greetings from Northern Maryland. It was quite a site to see two of the guys eating my plum tree. They are still there, no cocoon yet. I thought about posting an ad "My caterpillar needs a new home. I am having a terrible time training him and he wants to eat all my neighbors trees and pets. Are you interested?"

Should I let him live or use the insecticide to eliminate this critter?

Thanks for your assistance.
Al

 

Let him live! His parents are so beautiful.