The timing on this is very important. the adult thrip emerges from its larva stage in late april to early may, and then lays next years larva in early june..
so you want to spray for them about mid may (good timing on the post btw).
try using a residual spray like Dragnet or Talstar, that way if you miss some emerging larva, the residue will hit them.
You will need to spray a 6' radius around the tree aswell as the tree itself. Also, anywhere else that you have seen the thrips will need to be sprayed. If the thrips have made it inside the home; you will need to find the entry points (or just spray around the entire home) as well as spray inside foot boards and flooring. VERY IMPORTANT If you do need to spray the home use Dragnet, it is rated for indoor use.
As with all insecticides keep pets and children away from the applied areas for atleast 24 hours so none is ingested. If spraying in the home open all windows and doors and let the home air out for 5 or 6 hours to eliminate fumes
Hope that helps