(1) When you see a Monarch butterfly, you may marvel at its beauty. (2) They are larger than many other kinds of butterflies. (3) Also, their orange wings and black trim make them easy to spot. (4) Yet, beyond their beauty, there’s something else amazing about these handsome butterflies. (5) Scientists have discovered that Monarchs migrate thousands of miles each year. (6) In the early spring, they’re found in great clusters in southern Mexico. (7) By summer, the migrating Monarchs have appeared in the United States. (8) They’re even found as far north as Canada. (9) As fall leaves begin to turn, however, these great travelers gather for the trip back south. (10) You can often mark the end of summer by the absence of Monarch butterflies. What is the topic sentence of this paragraph?