Posted by: teatown | August 9, 2009

Monarch Butterflies

Monarch’s Incredible Migration About to Begin!


Male Monarch, Cape May, NJ (by Fred Koontz).

Each year, between August and November, we need only look skyward to witness one of nature’s most incredible migrations. Tens of millions of Monarch butterflies that spend the summer east of the Rocky Mountains fly to Central Mexico. Here, about 70 miles west of Mexico City, Monarchs survive the winter in 12  mountaintop fir forests at 10,000 feet elevation.

The Monarch is the only butterfly that migrates north and south very long distances as many birds do. This unique annual pilgrimage was only recently discovered, in 1975. Conservationists have worked ever since to protect this natural spectacle of evolution and adaptation, which depends both on protecting ecological health in the USA and conserving the relatively small land area in Mexico where all  of our eastern Monarchs spend the winter (except for a small additional population in Florida).

The Monarch’s journey is even more amazing when you understand the details of their “multi-generation” migration cycle. Unlike migratory birds, no single Monarch makes the entire round trip because their normal eight-week lifespan is too short. The Monarchs that overwinter in Mexico do not reproduce until after they start heading north, usually reaching Texas and Oklahoma, sometime in February and March. Their offspring (“second generation”) continue heading north throughout their two month life, as do the third and fourth generations, each generation making it further north until they reach northern USA and Canada. Millions and millions of Monarchs are produced along the journey north.  As fall and cold weather approaches, the last generation of the summer enters into a special non-reproductive phase, which allows these individuals to live seven months, or more. It is these longer living, fourth generation Monarchs that return to Mexico to repeat the cycle. The mystery to scientists is how do these butterflies separated by three generations know how to return to the same 12 mountaintops in Mexico! 

The female Monarchs lay their eggs on a variety of milkweeds, whose leaves the caterpillars feed on for two weeks after hatching from a four-day incubation period. Next, after a two-week pupal stage, the adult emerges from its chrysalis. The adults feed on nectar from milkweeds, butterfly weed, golden rods, and other plants.  If you wish to attract Monarchs to your property planting milkweeds is the best idea, as it feeds both adults and caterpillars.  You can easily learn to recognize the eggs, caterpillars, and chrysalis on the milkweed plants. Look for them!

Of the 142 species of butterflies that live in New York State, the Monarch is my favorite. So, it is disappointing to me that there seems to be very few this summer at Teatown or in the Hudson Hills and Highlands?  Leave a comment below if you have noticed the same paucity of Monarchs this summer and share your observations about  migrating Monarchs. Who will be the first to spot a migrating Monarch this season?

Now that August is here, I will be keeping an eye to the sky for Monarchs. You can tell when they are migrating (as opposed to flying for nectar or mating), because they seem to be moving in a purposeful straight path.  Also, if you follow a migrating Monarch toward sunset  – and if you are lucky – you might discover a roosting tree with dozens, even hundreds, of resting butterflies. If you want to learn more about Monarchs and follow a citizen-scientist project to track their migration visit the Journey North and Monarch Watch websites.  Better yet, take your family on a trip to Cape May, New Jersey, in September and October to witness thousands of these winged jewels heading south. Enjoy the Monarch migration — it is a miracle that unfolds each year right before our eyes!





  1. In past years migrating Monarchs have stopped to warm themselves on the stones in the local cemetery which has been surrounded by fields filled with milkweed and wild flowers. The fields however, are rapidly being covered with houses on small lots thereby depleting the Monarch’s feeding grounds. Some members of the adjoining meetinghouse are attempting to plant a butterfly garden near the cemetery which we hope will enable the Monarchs to sustain themselves.

  2. I live in Bowdoinham Maine and I have noticed a huge decrease in the monarch caterpillar and monarch butterfly this summer. I usually see the butterflies during the summer and collect the caterpillars in late Aug-early Sept. However, this year, I have not seen any caterpillars. I am very upset. My oldest son and I use to collect the caterpillar until they turn into butterflies every year. My son past away last year and I really want to continue our tradition of raising the butterfly. But I just can’t find any. Is there a reason why the Monarch is not around?

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s


%d bloggers like this: