In autumn, the leaves of the trees lose the chlorophyll and appear the colors that until then have been hidden: red, yellow, purple, etc. In fact, trees, in addition to chlorophyll, contain other compounds to be able to perform the process of photosynthesis, which are what we see at the end of the life of the leaves.
But for biologists Sam Brown and William Hamilton of Oxford University, color change means something else. They believe that bright colors are indicators of tree health, a strategy to ward off plant lice. Thanks to the bright colors, trees push plant lice to winter and choose other trees more vulnerable to reproduction.