Y is for Yellow Monday Cicada. The Yellow Monday cicada is the yellow form of the Cyclochila australasiae (the green form is the Green Grocer). Yellow Monday Cicadas lack a turquoise pigment that normally combines with the yellow pigment to form a green color. Visit the Scribbly Gum website for a photo and more information about Yellow Mondays.
Almost a Yellow Monday, this C. australasiae is mostly yellow and a little green: