With Halloween just around the corner, the colors black and orange are everywhere. But depending on where you live, you might have recently seen a whole lot of black and orange in nature—migrating Monarch butterflies. These amazing insects travel thousands of miles to escape cold weather and spend their winters in warmer climates in Mexico.

And monarchs aren’t the only butterflies with Halloween colors. Since the milkweed that Monarch catterpillars eat makes them poisonous, predators have learned to avoid them. Their bright orange coloring acts as a warning sign. Other butterfly species, like Viceroys, have evolved to mimic Monarchs’ coloring, which means that predators avoid them too, even though Viceroys aren’t poisonous. You can tell the species apart by the black line that cuts through the bottom portion of their wings—Viceroys, like the one in this picture, have it, but Monarchs don’t!

Photo by Benny Mazur