Consider going by a nursery, or even a 'Big Box store', nd get some BT ( Bacillus Thuringiensis), a natural occuring , organic control agent.
It will give them all an infectious flu which will kill them ; however, don't use if you are trying to attract butterflys.
Don’t listen to that advice! Do what I do. Take a Bic lighter and light up every one of those mudder fecking nests that you can reach! When the caterpillars fall, stomp the chit outta them!
Fire is organic, too...and stomping on them is SO satisfying!
:)