Monarch and viceroy butterflies are a classic case of mistaken identity. These two strikingly similar species, both sporting vibrant orange and black wings, often leave nature enthusiasts scratching their heads.
But don’t let the similar colors fool you: They are different species. This article dives into the key differences between monarch vs viceroy butterflies, giving you the tools to tell them apart.
Why does it matter? Monarch populations are declining, and accurate identification is crucial for conservation efforts. Learning to tell the difference can help you contribute to monarch butterfly protection.
Physical Appearance: Adult Butterflies
While both monarch and viceroy butterflies are orange and black, there are a few easy ways to tell them apart.
Size and Wingspan
In general, monarch butterflies are bigger than viceroys. The wingspan of a monarch is typically 3.5 to 4 inches, while a viceroy’s wings measure 2.6 to 3 inches across.
Wing Markings
The easiest way to tell the two apart is to look for a black horizontal line across the hindwings. If you see that line, you’re looking at a viceroy. Also, viceroys have a black “smile” marking on their wings that monarchs lack.
Wing Position During Flight
Monarchs tend to have a more graceful, floating flight pattern, while viceroys are more erratic fliers.
Caterpillar Stage: Key Differences
Even as caterpillars, monarch and viceroy butterflies look quite different.
Monarch caterpillars have a striking yellow-green body with black and white stripes running across it, and black filaments sticking out from both ends.
Viceroy caterpillars, on the other hand, have a mottled brown and white appearance. They resemble bird droppings, an evolutionary adaptation that helps them avoid being eaten.
These differences make it easy to tell these butterflies apart, even when they’re just caterpillars.
Diet and Habitat
Monarch caterpillars only eat milkweed. Milkweed contains cardiac glycosides, which makes monarch caterpillars toxic to many animals. In fact, monarchs cannot survive without milkweed.
Viceroy caterpillars, on the other hand, eat the leaves of willow and poplar trees.
These differences in diet are a clue to how these butterflies have evolved their mimicry strategies. Predators avoid monarchs because they taste bad and can make them sick. Viceroys “borrow” that protection by looking similar.
Mimicry: A Tale of Two Butterflies
Why do viceroy butterflies look so much like monarchs? It’s a story of mimicry, a survival strategy where one species evolves to resemble another.
Müllerian Mimicry
The viceroy’s mimicry of the monarch is an example of Müllerian mimicry. This is where two or more poisonous species look alike, reinforcing the message to predators to stay away.
Think of it as strength in numbers: The more butterflies that look dangerous, the more likely predators are to avoid them.
The Role of Toxicity
Monarchs get their toxicity from the milkweed they eat as caterpillars. They ingest cardiac glycosides, which make them taste bad and can even be poisonous to some predators.
Viceroy butterflies also consume toxins, although from different plants. Because both types of butterflies have a similar appearance and a similar effect on predators, the “warning signal” is amplified.
Migration and Overwintering
One of the most amazing things about monarch butterflies is their long-distance migration to Mexico or southern California. The butterflies fly thousands of miles to overwinter in warmer climates.
Viceroy butterflies, on the other hand, overwinter as caterpillars. This difference in behavior is another key way to tell the two species apart.
Frequently Asked Questions
Do viceroy butterflies eat milkweed?
Nope, viceroy caterpillars don’t actually eat milkweed! They primarily feed on willow, poplar, and aspen leaves. In contrast, monarch caterpillars exclusively munch on milkweed. This difference in diet is a key distinction between the two species.
What is the fake monarch butterfly called?
The “fake” monarch is the viceroy butterfly! While “fake” might sound a bit harsh, it’s true that viceroys evolved to mimic the appearance of monarchs. This is a survival tactic called Batesian mimicry, where a harmless species evolves to look like a dangerous one. So, the viceroy isn’t trying to be a monarch; it’s just trying to avoid becoming a snack!
Why do predators avoid the Viceroy Butterfly?
Predators initially avoided viceroys because they mimicked the monarch, which tastes bad due to its milkweed diet. However, scientists have discovered that viceroys are actually unpalatable themselves. This is due to the fact that viceroys eat plants that contain salicylic acid, a bitter compound. So, predators avoid them both because they look like monarchs and because they taste bad!
Final Thoughts
Monarchs and viceroys are easy to confuse, but they have key differences in size, wing patterns, and habitat.
Knowing how to tell them apart is especially important now, as monarch populations are declining sharply. With proper identification, we can better understand and support the conservation efforts aimed at protecting these iconic butterflies.