He reasoned that one of the species was distasteful to predators and that the usefulness of the bright coloring was to signal this distastefulness to the predator and thus increase its chance of survival. The other, similarly colored, species will also be avoided by predators and does not need to be distasteful. We now know that this is the case - The distasteful species is called the model and the similar, but not distasteful, species is called the mimic . The Viceroy, not closely related to the Monarch, is not distasteful but is also avoided by predators. There are many examples of Batesian mimicry in the insects.
Many insects are bee mimics.
Notice that the bee is a good example of a model, being brightly colored, often with stripes on the abdomen. The following are a bee mimic and a bee, specimens courtesy of Prof. Keith Waddington of the Department of Biology. The bee mimic on the left is a fly , a member of the Asilidae. The bee on the right is a member of the genus Bombus , a true bee. The fly has no stinger and is harmless but is colored and patterned just like a bee.