Just swipe your thumb through each leaf and squish the caterpillars. They are hard to control because the BT or other spray doesn't penetrate well inside the rolled up leaf. They will damage the fruit where they web up against the fruits surface. Just surface feeders but makes a mess of things.

I have a carey too, about 10 years old now. Yours doesn't look too awful to me. For what it is worth, I assume some leaves will be fodder for the wee beasties, as long as the healthy untouched leaves far outnumber the munched upon ones I wouldn't worry.

cut off a piece and bring it to your nursery. you may just have to wash off the ants, and use some tangle foot at the base of each tree to keep the ants from climbing up it again. you wrap some stretch tape (the stuff you use to train/tie climbing roses to a trellis) around the base of the tree, then paint on the tangle foot (its a sticky paste the ants can't climb past) on it. you have to reapply every year. good luck.

In addition to what Rhizo said about using Dawn For Dishes...instead of products actually designed for use on plants....Mr. Factory Owner uses whatever ingredients are available-for a given production run-at lowest possible cost. Thus, Dawn may behave one way one time, another way next time. Meanwhile, Safers and others have actual insecticidal soap sitting on the shelf, waiting to be used. And like he said....there's directions with that stuff. Couldn't begin to tell you all the ridiculous home-made concoctions I've heard and seen people use. Like my sister in law-who is not normally a dumb person-who nevertheless was proud as can be because she killed a lone buckthorn bush in her yard "without chemicals"! Heh...........I'm pretty sure the mixture of dish detergent, vinegar, and salt she used all consisted of chemicals! Plus, instead of using a tiny bit of herbicide actually labelled for such use, she now has salt in the soil in that part of her garden. She said she "understands" things like salt, vinegar, etc. but that the herbicides are a complete mystery. I would suggest she's clueless about both!