Naturalists are beginning a transcontinental flight -- following the path of
the longest insect migration in the world: the Monarch butterfly's flight
each autumn from Canada, through the United States, to Mexico. Carolyn
Weaver has more.

[OPT] Like all butterflies, the Monarch begins as a caterpillar, inching
along on tiny legs, feasting on leaves. Then comes the slow
transformation inside the chrysalis: from worm-like creature into a thing
of wings -- and beauty. [END OPT]

Monarch butterflies, instantly recognizable for their gold and black
markings, are found in many places around the world. But only those east
of the Rocky Mountains in North America make the annual autumn
migration. From their summer habitats in the north, three-hundred million
butterflies fly south - more than 5,000 kilometers -- to a few small
forests in Mexico. And that's the path that this unusual ultralight aircraft
will follow this year - piloted by a crew of documentary filmmakers,
including lead pilot Francisco Gutierrez:

"This craft is made in England, but I designed all the stickers on it.
Basically, the idea is to make people aware that we have to take care of
our world. And I found in this incredible insect, the Monarch butterfly, a
very magic and amazing phenomenon."

Pilots from all three countries will take turns flying the motorized glider
from Canada through the United States to Mexico. The butterflies will
determine the flight schedule.

"Actually, if the Monarchs fly, it's because we have good weather. If
they don't fly, it's not good, so I'm just trying to follow (their) rules. So,
if I fly with them, I will be ready." [OPT] Reporter: So they take a
break if the weather is bad? "Yes, when they have a thunderstorm, they
stay somewhere, I don't know where. And when the weather is good
again, they fly." [END OPT]

"To me, the Monarch is a symbol of the interrelatedness of all animals
and plants."

Monarch butterfly expert Lincoln Brower says that large-scale
agriculture's herbicides and gene-engineered crops are killing off
everything else, including the plants that butterflies eat.

"The biological diversity of all the native plants is being totally

In Mexico, meanwhile, illegal logging is destroying the high-altitude
forests that the Monarch butterflies shelter in over the winter.

"The Monarchs depend on the trees to get through the winter. So, if they
lose that over-wintering habitat in Mexico, at some point the straw will
break the camel's back and we'll lose the whole migratory phenomenon."

The species itself isn't endangered, but Dr. Brower says that the
migration is both a beautiful natural resource, and well of scientific

"For example, right now there's a current controversy as to whether the
Monarch is capable of detecting magnetic lines of force. The fact that
these little guys can fly from Toronto to a pinpoint on the map in Mexico,
nearly 2,000 miles, how do they do it? What clues are they using? How
is their brain processing this information? [OPT REST OF BITE] I
mean, the brain of a Monarch is about the size of a small steel pinhead,
and yet within it is the capacity of navigation comparable to the highest
humans have, or even higher, for that matter." [END OPT]

The pilots of Papalotzin, as the motorized glider is called - the word
means "little butterfly" in the ancient Aztec language - must depend on
cruder navigational tools as they track the clouds of butterflies south.