Violent 3yo - WWYD?

[Sandbox Sally]

I have had dcb for 8 months. I have had issues with his parents, but that's not his fault, and I did usually enjoy having him.

I've edited to add that he's not quite 3 right now. He will be in a few weeks.

Recently (since after Christmas) he's been hitting, throwing, telling me no, kicking...well you get the idea. My 13 year old dd and I saw him outside our house last week kicking and biting his mother. His mother did nothing, at least while they were still here.

Today, when I was trying to get him to come to circle time, he turned with a wooden tractor, screamed, "NO!" and hit me square in the face with it. It really hurt. I saw red, and had to walk into the other room to cool off. After I calmed down, I went back and talked to him. He refused to apologize, and kept laughing at me.

I know he's only a toddler, but he's pretty much terrorizing the daycare right now. He regularly pitches fits like this and throws toys. Sometimes the other kids get hit. I've caught him hurting his own sister on purpose - she's 11 months old.

There must be something going on with him. But, I am not a psychologist, and I only see him three times a week. I really don't know how to quell this. I have tried reasoning, positive reinforcement, and consequences such as sitting out. So far, he's not responding. It has been 2.5 months of trying, and I'm getting nowhere.

I don't know what to do. I have told his mom a couple of times, and she kind of blows it off. Is this worth giving notice for? Would it be fair of me to give him a letter stating that if he does something like this again, he will no longer be welcome in my program? It's not his parents' fault, and I know there's little they can do to stop him from being violent another time, but I am sick and tired of waiting to get hit or kicked. Today, it was a heavy toy, and I am NOT pleased. He could have broken my nose or my glasses.