Müllerian Mimics

Müllerian Mimics
Some of the insects that mimic bad-smelling, inedible lycid beetles are harmless Batesian mimics. However, lycid beetles also have mimics that are just as sickening to predators. These mimics include bad-tasting beetles and moths as well as stinging wasps. They are all Müllerian mimics—harmful animals that mimic other harmful animals. Müllerian mimics are also called “co-mimics.”



It may seem strange for an animal that has defenses of its own to mimic another animal. A stinging wasp and a nauseating moth, both with warning colors, can easily educate predators to leave them alone without mimicking a nasty beetle. This kind of mimicry, however, may have developed because it benefits the models as well as the mimics. They share the task of educating predators, and they also share the danger of being caught by a predator that has not yet learned to leave them alone.

The colorful Heliconius butterflies of tropical Central and South America are among the best examples of Müllerian mimicry at work. There are more than 40 species of Heliconius butterflies. As caterpillars, they feed on the vines of poisonous passion plants. Their bodies become poisonous. Later, they grow to be poisonous butterflies with black, red-orange, and yellowish wings. The butterflies also give off strong smells, which may help warn predators that rely on smell more than sight. Heliconius butterflies of different species resemble each other, so predators that learn to avoid one species will then avoid similar-looking butterflies of other species. The butterflies employ Müllerian mimicry across the range of places in which they live. Butterflies of one Heliconius species in a particular place may look different from butterflies of the same species in another place, but their co-mimics look different in each place, too.

Heliconius butterflies, in turn, are mimicked by butterflies that are not related to them. Some of these butterflies may also be poisonous, but others are not. Some are not butterfl ies at all, but day-flying moths.

The links among these insects are so complex that scientists put them in groups based on colors, not by kinds: “tiger,” “red,” “blue,” “orange,” and “transparent.” These groups are called mimicry rings.

Species of poisonous burnet moths also wear warning colors in different patterns of red, black, yellow, and white. These day-flying moths are found in much of Europe, Africa, and Asia. Their bodies make a strong acid that’s carried in their blood. Species of burnet moths living in the same area look similar to one another. They share their habitat with unrelated poisonous moths that look similar, too.

Pacific beetle cockroaches are also Müllerian mimics. These cockroaches spray a foul-smelling fluid from the sides of their bodies at ants and other predators. They look and smell like darkling beetles, which tip forward when threatened to spray a stinky fluid. They are often called “stink beetles” as a result. (A Batesian mimic, the cactus longhorn beetle, copies the darkling beetle’s behavior but does not have any smelly spray.)