Control Caterpillars With Synthetic Insecticides
Control with Pyrethroid Insecticide
Any of the pyrethroid insecticides will control caterpillars as long as you make direct contact with the insect when you spray. Go to Yardener's Tool Shed and see the selection of options available in the file Synthetic Insecticides.
If you need a sprayer, go to Hand Tools For Spraying in Yardener's Tool Shed.