One day I found myself in a dream. I still can’t believe that I spent several days among hundreds of thousands of these beautiful creatures in Mexico. This amazing butterfly is called the danaid monarch. It is the only butterfly that migrates. From North America, thousands of monarchs fly to Mexico every year to spend the winter, breed, and fly back. The duration of the flight is much longer than the duration of their life, and the butterflies often return after wintering already in the second generation and flown away. Great-grandchildren.
Those butterflies that are born at the beginning of summer live for 2 months, but those that were born at the end of summer and are going to fly for the winter enter a special phase of existence – diapause. The non-reproductive phase of life, when butterflies are in a physiological state of torpor that slows down the aging process, allows monarch butterflies to survive the winter. Therefore, all those butterflies that are in the Biosphere Reserve in the State of Michoacán do not really live a full life, but are in a daze. Although they fly very actively.
I do not recommend visiting the reserve on days without sun – at this time, butterflies sit on branches and motionless on each other. They need to warm up to fly. Many tourists leave disappointed if they come in cloudy weather.
In the spring, after the butterflies wake up, they produce offspring. The stages of caterpillar and pupa last about two weeks, then adult butterflies – descendants of insects migrating in autumn – return to their habitats. On the way, the butterflies lay their eggs and then die, and the flight is continued by their children, who also breed during the migration. Great- and great-great-grandchildren of butterflies that flew away to warmer climes in autumn return to their homeland. The second, third and fourth generations of insects return to the northern regions of the United States and Canada.
The danaid monarch is one of the few insects capable of making flights across the Atlantic Ocean.
The most numerous populations are found in North America. This species is found in Africa, Australia, and in some European countries such as Sweden and Spain. Monarchs can be found in the extreme southwest of Great Britain, on Lake Bennington, in Walla Walla, Washington, the Far East, New Zealand, North Africa and the Hawaiian Islands. Settled danaid monarchs live in Bermuda, Florida, Arizona and the Caribbean region, as there is a mild climate all year round.
It is often asked why such a cluster of monarchs are not eaten by birds. The milkwort, preferred by caterpillars, is poisonous and disgusting in taste to birds. There are a lot of cardenolides in the juice of the milkweed – substances that are not only unpleasant for bird taste, but also cause nausea in small concentrations, while a large dose can cause a heart attack.
The poison obtained from the leaves of the plant is stored in the body not only in caterpillars (the fact that the caterpillars are poisonous is evidenced by their bright color), but also in butterflies, being distributed throughout the body. Therefore, butterfly colonies that are in suspended animation survive, as birds prefer to feed on less poisonous insects.