Tecoma stans or Arizona Yellow Bells and caterpillar damage

I keep seeing a lot of questions about the damage to the Yellow bells and the Orange jubilee plants we have in the valley and never see a lot of solutions.

These beautiful plants do get a caterpillar that can leave the entire plant looking like it was set on fire.  I live in a neighborhood that has a landscaping company that appears to be totally inept when it comes to dealing with these little worms and they just shave the entire bush down to the nubs in the fall (which is the absolute worst time to be pruning stuff down to the nubs in the outskirts of metro Phoenix but that will be the next blog) rather than just spray some bacteria on them to kill the caterpillars.

The Bougainvillea get the worms also and Bt is such an easy non chemical method to control the infestation I don't understand the people that cut the whole thing down rather than simply treat the problem.  They would be blooming profusely right now in such beautiful color if they were treated a few weeks ago.