Expression of y^+t7.7 is good in larvae, allowing straightforward selection of the balancer in an otherwise y^- background. In adults, however, essentially all show some degree of variegation.

The degree of variegation of y^+t7.7 in CyO-vWb is background dependent. In most BDGP insertion lines carrying this balancer, y⁺ expression can be detected only in a few macrochaetae and in the presutural, super alar or post alar bristles. Some lines, however, have much more extensive y⁺ expression in adults.