In the pitcher of your blender or bowl of your food processor, add the arugula, basil, garlic, parmesan cheese, pine nuts and a dash of salt and pepper. Blend, while slowly drizzling in the olive oil until the pesto comes together and is smooth. Scrape down the sides of the bowl if you need to. If you need more olive oil, drizzle more until the pesto is smooth. Set aside until you are ready to use, or store in an airtight container in the refrigerator for 2-3 days.