Sounds like you have caterpillars! Little green caterpillars decimated my petunias one year before I realized what was going on. They eat holes in the flowers, bigger and bigger, and then move on to the buds, eventually eating everything. The best thing to eradicate them is something called “Bt”, and it works fantastically well. It’s a spray you can find at garden stores that contains Bacillus Thuringiensis. You can read more about it, but it is 100% effective against caterpillars.
That tree definitely needs water! Their leaves aren’t supposed to be limp. You should be able to easily tell if it needs water by feeling the weight of the pot.