|One of the first and most obvious things to note when you spot a butterfly is its size. You will discover that butterflies generally come in one of three basic dimensions: small, medium and large. This system may sound ridiculously arbitrary at first, but when you begin to regularly observe several different butterflies together in the field, these categories quickly start to make sense. For a starting point, follow this simple strategy: the next time you see a Monarch butterfly, pay close attention to its size. You may wish to use your hand as a reference. Most Monarchs have a wingspan close to the length of your palm (about four inches) as measured from the base of your fingers to the start of your wrist. This is considered a large butterfly. From here it's basically a matter of fractions. A medium-sized butterfly by comparison would have a wingspan of generally about half that size (about two inches). Finally, a butterfly would be considered small if it had a wingspan one quarter that of a Monarch (around one inch).