Spring migration is underway - not just for birds but also for Monarchs. The northern most Monarch sightings this week have been in Maryland and Indiana and they will likely show up in Vermont towards the end of May.
Which of the butterflies pictured below is a Monarch?
Click below to reveal the answer to this weeks’ quiz!
The picture on the right shows a Monarch and as we learned from the Week 4 Quiz, this is a male Monarch due to the pheromone patches or androconia on his wings. The butterfly on the left is the lookalike Viceroy.
Both butterflies are about the size of your credit card and orange with black stripes but you can identify the Viceroy by the black PM line that cuts across the middle of their hind wing like a smile. The Viceroy was originally thought to be a Batesian mimic of the Monarch, a term we learned in the Week 15 quiz that refers to a harmless species that copies the appearance of a toxic one. However, when the Viceroy caterpillar snacks on Willows, they concentrate salicylic acid in their bodies making them bitter and unappetizing to predators. This makes them example of another form of mimicy - Müllerian mimicry, where two toxic species come to adopt the same appearance to increase the effectiveness of their warning colors.
Since last week, the monarchs have continued their flight northwards with their closest sighting being in New Jersey.
Male monarch by sm40052 (iNaturalist)
Viceroy by Jill DeVito (iNaturalist)
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