Some entomologists believe that the evolutionary reason that plants expend energy to produce fall color is to warn pests. A plant that is healthy is able to produce lots of carbohydrates, and therefore more anthocyanins. Some insect pests will not lay eggs on bright colored leaves. Instead, they will find a “weaker” drab/dull colored tree on which to lay eggs. Some scientists believe that anthocyanins may act as a sunscreen to inhibit the destruction of the chlorophyll, help to prevent frost injury to leaf tissues, or limit water loss during dry spells in autumn. As far as the fall foliage watcher is concerned, their purpose is simple—they signal a last hurrah for the growing season and delight the optic nerve.

Summarize the last paragraph to explain the proposed evolutionary reasons that plants produce fall color in 30 words or less.