I came across this red milkweed beetle (Tetraopes tetrophthalmus) while on a walk a few evenings ago. They are part of the milkweed ecosystem and not harmful to milkweed plants or monarch butterflies.

The beetles are adapted to eat the milkweed plant, which is toxic to many species of animals. Because they ingest these toxins, the beetles, like monarch butterflies, are in turn toxic to many predators. The red milkweed beetles are brightly colored, advertising their toxicity to potential predators. I learned that the use of these kinds of signals as a defense mechanism by a wide range of animals is referred to as “aposematism.”

We can see this in monarch butterflies, poison dart frogs, skunks, blue-ringed octopuses, black widow spiders, and many other animal species. There are even animals that mimic aposematism in an attempt to ward off predation.