Thumb, Sweet Thumb

My son is a thumb sucker. Not an occasional thumb sucker, but a full-time thumb sucker. His sucking is not limited to sleepy time. No, he sucks in the car and while watching TV. In the middle of playing, he often will retire to the couch for a quiet suck. The thumbnail on his preferred thumb never grows. I suppose any growth is sucked right off. It is often puckered and pruney. He loves his thumb.

It was no surprise to us that Sweet Pea took to thumb sucking. One of his ultrasounds showed him sucking his thumb in utero. For the first three months of life, he had a paci. We were never without a paci. We had pacis in the crib, in every room of the house, in the diaper bag, in the car, buried under the couch cushions, in the laundry basket. Everywhere. He loved them.

Then, at three months, he found his thumb and he never looked back. I would try to give him his paci, but he spit it out with a snarl, look at it with disgust, and shove his thumb back in his mouth.

I allowed the thumb sucking because, well, I was a thumb sucker. Until the age of 9. Really. I distinctly remember the feeling of comfort and peace that would wash over me as I sucked my thumb with my sock doll Polly in hand. I would hold her leg in my sucking hand and rub her softness against my nose as I sucked. All was right with the world. How cruel would I be to deprive my son of that pleasure?

Now, however, my leniency has come back to bite me in the ass. At 3 1/2 Sweet Pea is sucking as much as ever and it is affecting his speech. We had his speech evaluated and it is still within the normal range, but just barely. He has a frontal tongue protrusion caused by sucking and can not pronounce words correctly. There are times that we can not understand what he is saying because of the mispronunciation.

We need to limit the thumb sucking, but how? I can't make him totally quit. I have no control over what he does at nap time and nighttime. I can remind him during car rides and TV time to take his thumb out of his mouth, but what else can I do?

Suggestions?