Ethiopian harrar coffee beans contain 1.13 percent caffeine. This amount of caffeine doesn’t seem to harm the Ethiopian Coffee Bean Beetle or Ethiopian Harrar Beetle, for whom the coffee bean forms a major part of its diet.
When fully grown, these beetles are about two inches in length. They have very powerful jaws and are able to nip off the beans from the plants with ease. These beetles work in teams, two longer beetles on the plant and eight shorter beetles underneath, picking up the beans and rolling them back to their nest.
The beetles don’t push or even pull the beans, but balance on them and roll them back using a combination of back and front legs. The nests of these beetles are always at the bottom of slopes, so that once a beetle has rolled a bean to the top of the other side of the slope, the bean will roll down towards the nest under the influence of gravity. There are normally four or five beetles outside the nest entrance, who will guide any errant coffee beans into the entrance, where the storekeeper beetles roll them into the larder. Here the chief beetle assesses the hardness of the bean. If it’s an immature bean it will be allowed to ripen, but mature beans are set aside for immediate consumption.
This is an extract from the book Animals Evolution Avoided