Here's the latest snapshot of this spring's migration, thanks to Macalester College student Colin Maher. This map shows the extent of the migration as of April 15, 1997. In each of the 4 seasons we have tracked spring monarch migration, the first Massachusetts sighting has occurred after May 16th. Be sure to read the discussion below about this students' unusually early observation. On the left-hand side of this page you'll see an owl button.
Viceroy butterflies look exactly like monarchs to the untrained observer.
This toxin concentrates in the larva's body and is still there when the butterfly becomes an adult. Predators know to avoid eating monarch butterflies because of this poison. As we track the monarch butterfly migration each spring, we must always be concerned about accurate identification. Pull out your field guide to butterflies and make sure you can tell the difference between monarchs and viceroys. Look at the milkweed plant carefully and sketch it in your field notebook.