Use the picture below to answer the following question. Scientists observe insects called walking sticks living in the California mountains. The insects look like plants on which they live.

The walking stick population has two patterns:

Some have striped patterns on their bodies and are usually found on striped chemise plants.
Some have no stripes and are usually found on non-striped lilac plants.
Describe how the theory of evolution is supported by the walking stick population, and predict how the walking stick population would change over time if the lilac population was rapidly reduced by a virus.