Hops are herb plants that grow vines and cones. The cones have a substance called lupulin that gives the cones its flavor, and different types of hops have different types of flavors. People have used hops throughout history to flavor foods and beverages. Many insects do not like hops, so people also stuffed their pillows with the cones to keep insects away. An except is wasps, who use the leaves to build their paper nests.