Threats and Sighs

So we've been having a little problem with Baby M for the last week or so.  At three and a half he has started biting.  He never bit anyone before, but now he does.  Hard.  And he doesn't let go until you physically unclamp his jaw from your arm.  On the plus side, he only bites my husband and me, but really, is that much of a plus?  We ask him why he is biting and he replies "I don't know."  We've told him biting is unacceptable, that it hurts us, that he should use his words, that if he is angry or frustrated he can bite a pillow.  None of these statements have had any effect. He bites seemingly without cause or provocation.  Yesterday he leaned over and bit me while we were eating dinner.  Tonight he bit my husband while getting into the bath.  I suspect that he is biting because he feels he's not getting enough attention, and we are doing our best to spend dedicated time with him, but we still really would like the biting to stop.

Today I was sitting on the couch with the boys and I saw Baby M lean in for the bite.  Tired, angry, tangled up with Baby S and unable to move away I said, "If you bite me you cannot play your Super-Grover game on the computer." (I'd told him he could play it after lunch.)  He paused for a moment and then sunk his teeth into my wrist.  In theory I don't believe in threatening children, especially with "consequences" completely unrelated to the problem behavior.  But in practice?  Well, stuff happens.  But today I was reminded why I try not to use threats.  As soon as I said "Ok, no computer game" he started the tantrum to end all tantrums.  He screamed and cried for about an hour (apologies to my neighbor with the open house).  The tantrum I could handle, but then he told me "The thing that will make me stop biting is if you let me play a game."  Not exactly the message I was going for.  Later that night I overheard Baby M relating the episode to my husband.  His explanation of what happened was "Mommy took away my game to make me frustrated because I made Mommy frustrated when I bit her."  Again, not really the lesson I wanted him to learn.  Furthermore, Baby M bit my husband about 15 minutes prior to this conversation, so aside from not teaching him anything useful my threat didn't curb the problem behavior either.

I'd like Baby M to learn that biting is wrong because it hurts people and understand that hurting people is wrong.  I'd like him to learn to express his feelings and ask for what he needs.  I am just not sure how to teach him this. I talk about treating people with respect. I try to label his own and other's feelings.  Our number one house rule is that we do not hurt people or animals.  I just do not know what to do.  Sigh.