Monarch butterflies have been described as one of the most remarkable animals on Earth by many scientists. What makes them so amazing is that they travel in excess of 2,000 miles from Canada to Mexico. You might expect this from a stout, well muscled animal like a Canada Goose, but a butterfly is one of the most fragile insects on the planet. Throughout their journey they have to survive cold, heat, storms, high winds, predators, and pesticides. And millions of them succeed on wings thinner than paper and bodies that weigh less than a fifth of an ounce.
How do they do it? Don’t ask me. Nor anyone else either. Scientists are stumped but they’re starting to understand a few things better. In fact, the migration wasn’t discovered until 1975 when Monarchs tagged in Canada were discovered high in a mountain pass in Mexico.
For one, the round trip journey occurs over four generations of Monarchs. Surprisingly, it’s not an equal distribution of four months a generation. It takes three generations of Monarchs to travel from Mexico to Canada with each generation surviving about a month. It takes the effort of the fourth “super generation” to make the entire trip from Canada to Mexico and the first leg of the return to the Gulf States over a period of 9 months.
If you come across a Monarch caterpillar like the one pictured you can determine the generation by your location and time of year.
The Monarchs depart from their Winter sanctuary in Mexico and begin to head towards Texas and the gulf states. Some make their way to California and the west coast.
Mid to Late April
The second generation begins as the migration stretches across the southern states and across middle America. Some hardy survivors from the first generation still hang on.
Mid to Late May
The third generation begins to show up in the northern states of the Midwest, the west coast and northeastern states. This is the generation that will finally begin to arrive in Canada thru June to lay the eggs for the super, fourth generation.
June is the month for the fourth generation. This fourth generation will emerge from Canada, the northern, west coast of the U.S. and the northern United States from Minnesota to Main. This is the generation that will feed on nectar through the summer and begin it’s long journey to Mexico in August.
Just so you know, the Monarch caterpillar pictured in this article was photographed in far Northern Illinois on June 18th of this year. That makes it one of the super generation that will make a 2,000 mile sojourn totally unique on the planet.