SEPTEMBER
1996

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

9-26-96

Magnificent Monarch Migrators Are Magical

Each fall, during September and October, monarch butterflies from across North America can be seen moving to their overwintering grounds in Mexico. The migration begins in the northern part of the monarch range, in parts of Canada.

This remarkable movement of insects is somewhat like an avalanche in that it grows in size as it moves. Local monarchs join the throng as they flutter lazily southward. The original Canadian butterflies are soon accompanied by those from Michigan or New York. By the time the monarchs reach the Mexican border, insects from all of the eastern states have succumbed to the urge to go south.

Like an avalanche or a glacier, the monarchs seem to flow along certain routes. The butterflies don't like to fly across water and prefer to stay over land. Many Canadian monarchs cross into Michigan from Port Huron to Detroit because they are being funneled southward between Lake Huron and Lake Erie. In the same way, the migrating butterflies tend to flow along the Eastern Seaboard and across the Gulf Coast states on their way to the overwintering grounds.

The magnificent migrating monarchs also come together in groups along the route for reasons other than to stay over land. One of the most spectacular is when they go to roost at night. Monarch butterflies, like all butterflies, do not fly at night, so when the sun sets so do the monarchs.

Roosting monarchs generally gather on the same tree. With wings folded in the resting position, the insect hangs from a branch and, at first glance, resembles a leaf. These butterfly trees are an impressive sight in the morning when the rays of the fall sun warm up the overnight monarch guests. The butterflies begin slowly opening and closing their wings, and the tree appears to come alive.

Some trees just seem to become a resting place for monarchs year after year. In other situations, a tree may become a gathering place for several nights even though it had never been used for that purpose before. In either case, humans who see it have been treated to one of the true miracles of nature.

Monarchs on the move need energy for flight. They get this energy from nectar. Thus, many, many monarchs can be seen sipping nectar or flitting from flower to flower. In the Midwest, goldenrod flowers provide a good nectar source. Hundreds or thousands of monarchs might frequent abandoned meadows ripe with goldenrod during the fall migrations.

Monarchs never seem to be in a hurry as they migrate. And they aren't. After all, it's a long trip — sometimes 2,000 miles — and butterflies aren't built for speed. The monarchs generally follow the fall from north to south, arriving at the wintering grounds sometime in November. All of that travel time provides more opportunity for us humans to marvel at the magic of the monarch migration!

 

Writer: Tom Turpin
Editor: Andrea McCann