There’s a species of jewel weevil called Pachyrhynchus reicherti. It has a black and spotted body. Its elytra are joined together. It’s too tough to bite through. Its strong colors and markings tell predators to stay away.
When Cabras first spotted a new species, Metapocyrtus willietorresi, she thought it was Pachyrhynchus reicherti. It has similar colors and markings. It has a tough, joined elytra. Neither beetle would make a good meal. So, why was one copying the other?
It’s called Müllerian mimicry. That’s when two equally harmful things have developed to look like each other. They send clear signals to predators to stay away.
A third beetle, Doliops daugavpilsi, looks a lot like the other two. But it’s a longhorn beetle. It has a soft shell that predators could bite through. By having colors and patterns similar to the weevils, the longhorn stays safe. It keeps predators away by looking dangerous. This is Batesian mimicry.
Here are a few examples of the beetles Cabras saw during her fieldwork on Mindanao. The mimics strongly resemble their models.
To test a hypothesis, Cabras used fake beetles made of modeling clay, like the one shown here. She wanted to see if predators would react to the beetle’s warning colors.
Testing a Theory
Cabras wondered if she was the only one being fooled by these mimics. She tried an experiment. She made fake beetles from modeling clay. They looked like Pachyrhynchus reicherti. She set them out in places where the beetles were common. She set them out in places where they were not common. Then she set up cameras.
Where the beetles were common, predators stayed away from the clay beetles. They knew what the colors and patterns meant. In the places where the beetles were not common, predators tried to attack. They had not yet learned to stay away.
In Mindanao, there could be many new species to discover.
Cabras still has many questions. But land on Mindanao is being cleared away for farming and houses. In a few years, she might not be able to find these beetles in their natural habitat. So for now, her eyes are trained on them.