Do not cover the exit areas with a defensive mechanism which runs the larva back into the body cavity. If close to the skin surface, clean the area with alcohol, take an exacto knife with a new blade, clean it by sterilizing with alcohol set ablaze while on the blade. Cut a slice of skin downward so that the caterpillar can escape. No I'm not crazy, that larva can cut tunnels throughout your body cavity and even the brain matter.