I have a beautiful potted lemon tree and this is the first year I have ever seen these "huge" caterpillars on my plant. One day there were none the next day there were ten. Over night they ate practically 60% of the leaves. Looking on websites I really haven't seen one. It has the markings and colors of a Texas rattlesnake. I know that sounds crazy but they are evil looking. PLEASE HELP my beautiful lemon tree.
A cheap and very effective remedy is to put a bit of dish detergent diluted in water in a spray bottle and spray the plant. The soapy water won't hurt the plant but will get rid of the caterpillars. If that don't work try Sevin powder.