Why might the survival advantage of the red aphid morph fluctuate?

The risk of predation varies depending on local context like background foliage or predator activity

The selective pressure exerted by natural enemies, such as parasitic wasps or ladybugs, does not apply uniformly across all environments. The visibility of an aphid morph—be it red, green, or yellow—is highly context-dependent. A red morph that might be easily detected against the standard green leaf of one host plant might achieve superior camouflage when feeding on flowering plants or senescing foliage. Similarly, specific predators might target certain colors only during particular times of day or under specific lighting conditions. This complexity means the interplay between color polymorphism and predation risk is dynamic; the advantage shifts as the local context of background, enemies, or foliage changes, thereby contributing to the maintenance of polymorphism.