I have big green catapillars eating my hibiscus. what can I do?

Answer 1

For a single plant a ready to use spray bottle of a contact insecticide like this will do it:
https://www.domyown.com/monterey-houseplant-insect-spray-p-11260.html
For a larger planting where you need to mix your own in a sprayer, this is a similar pyrethroid insecticide:
https://www.domyown.com/dfense-sc-p-1809.html