I'd say that there are a few things wrong besides the caterpillars.
Bt (dipel or Thurgicide) sprayed on the tree will help to deal with the caterpillars.
The sucking insects can usually be taken care of with soap or horticultural oil once a week. If you use the oil, do not use it on a day that exceeds 80 degrees or it can burn. Use it early in the morning when the leaves are cool.
Try to feed the tree and make it as healthy as you can. Stressed plants attract more pests than healthy ones.
I don't know what kind of tree it is but it has a lot of small twiggy growth and the dead wood and crossing branches should be removed. Pruning is an art and if done badly will ruin the tree forever, so it is better to find someone who knows how to do this to help you. Pruning out dead and crossing branches though is easy, just don't get gung ho and keep chopping. A little at a time gives the tree time to recover and you really need to stand back a bit and plan what needs to go and what needs to stay, that is where having someone who knows what they are doing helps.
Happy gardening in Hawaii. Gardens are where people grow.