using some color study skills I learned in a botanical illustration class, I only needed to use five prisma colors for this Pelidnota punctata (grapevine beetle) sketch.
light brown - true blue, orange and a touch of canary yellow
dark brown - aquamarine, poppy and a touch of orange
before the class I would have used at least four colors to make up one. simplifying helps prevent muddied colors and saves time.