What is the longest distance traveled by a Monarch butterfly

Exceptionally, an individual of this species flew 2112 km in 46 days. This favors the dispersion of the species, which has occasionally been found even in areas very far from the original range

by Lorenzo Ciotti
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What is the longest distance traveled by a Monarch butterfly

Monarch butterfly is distributed throughout most of America, from southern Canada to the Amazon River. Since the 19th century it has also been found in Indonesia, New Zealand and Australia, where it is known as a migratory butterfly.

In Europe, it is resident in the Canary Islands and Madeira, while migrant individuals occasionally appear in the Azores, Portugal and Spain. The populations of North America carry out periodic migrations between the northernmost regions, where it is present only in the summer season, and the wintering areas, orienting themselves with a special sense called magnetoreception.

In autumn the butterflies fly south, forming groups of thousands of individuals. Those of the western United States reach some mountainous areas of California between San Francisco and Los Angeles, where they spend the winter in a state of semi-hibernation clinging by tens of thousands to the trunks and branches of trees.

Those of southern Canada and the central and eastern United States reach a small valley located in Mexico at 3000 m a.s.l. above sea level, where during the winter more than 14 million butterflies concentrate on a hectare and a half of surface.

In the following spring, after mating, individuals of both sexes begin their return journey, during which some females stop to lay their eggs. Both the larvae and the adults have lively aposematic colours, which defend them from vertebrate predators, warning them of the presence of toxic substances which make them unpalatable.

These substances are assimilated during the larval development by the species of Asclepias on which the caterpillar feeds.
It has a remarkable resistance to flight which allows it to make long migrations. Exceptionally, an individual of this species flew 2112 km in 46 days.

This favors the dispersion of the species, which has occasionally been found even in areas very far from the original range. The monarch is the first butterfly to have its genome sequenced. The 273 million base pair draft sequence comprises a set of 16,866 protein-coding genes.

The genome provided researchers with insights into migratory behaviour, the circadian clock, juvenile hormone pathways and microRNAs that are differentially expressed between summer and migratory monarchs. More recently, the genetic basis of monarch migration and warning coloration has been described.

There is no genetic differentiation between the migratory populations of eastern and western North America. Recent research has identified specific areas in the monarch's genome that regulate migration. No genetic difference has been seen between a migrant and a non-migrant monarch; the gene was expressed in migratory monarchs, but not in non-migratory monarchs.

In 2015, research identified genes for bracoviruses, present in wasps, in the genome of the North American monarch, leading to articles about monarch butterflies as genetically modified organisms.