The Qodiac is like the Zodiac but better, because you can calculate it using only your (Gregorian) date of birth.
Take the month and the day of the month you were born and convert them into numbers (e.g. January 1 = 1/1). There are four moon fairies whose orbits your month and day of birth can coincide with. Magicicada Major stops by on months that are prime numbers (February, March, May, July, and November), while Magicicada Minor stops by on days that are prime numbers (so the 2nd, 3rd, 5th, 7th, 11th, 13th, 17th, 19th, 23rd, 29th, and 31st of every month). Armadil Major stops by on months that are square numbers (so January, April, and September), while Armadil Minor stops by on days that are square numbers (so the 1st, 4th, 9th, 16th, and 25th). This means that about 60 people will have no such fairies in their midst.