Grammadot
Your caterpillar looks like a sawfly larva. I could not find one that specifically eats spicebush. There are some that are white in the early instars then when they molt to the last stage they are the regular yellowish with black spots.
The adults look like small wasps usually black with yellow or orange on thorax or abdomen.
Control is to pick them off or spray with insecticidal soap or horticultural oil.
Here are some photos of adults and larva.
http://bugguide.net/node/view/19836/bgimage?from=24
Great photos!
Hope that helps a little.
