Day 16 – What Patterns Do You See? Painted lady butterfly showing its ventral wing pattern (underside) © Labbradolci. CC-BY-NC 2.0. The patterns on dorsal and ventral surfaces of butterflies are typically different because they have evolved different functions. The ventral side (underneath) is often used for camouflage and predator avoidance, when the butterfly is resting. The usually brighter, dorsal side (top) is used for signaling and finding a mate. Wing patterns and colors are controlled by a master gene, WntA.