If you’ve been walking in the desert section of the PCT you have probably seen the large population of hummingbirds. And you’ve probably seen them hitting up flowers, mostly red flowers. And the insects mostly hit up the yellow, white and blue flowers. But why? The answer is pretty damn cool. Hummingbirds are attracted to red flowers and these flowers are usually tubular, allowing for almost only hummingbirds to pollinate them. The firecracker penstemon is the prime example.
Birds like these colors because they are very bright and showy against the desert background, but it interestingly, insects are hardly attracted to these flowers at all because most insects can’t see red. They see farther in the other direction of the electromagnetic spectrum and so are sensitive to blues, violets, and even ultraviolet light. Indeed some flowers like evening primrose have designs in ultraviolet that we can’t see without special filters.