Zoom on the monarch butterfly in Canada

the monarch butterfly is one of the most recognized butterfly species in the world. In Canada, this animal species is found from Alberta to Newfoundland. Its most important breeding grounds are in the southern regions of Ontario and Quebec. A small portion of the monarch butterfly population also lives in the southern part of British Columbia. Zoom on the monarch butterfly in Canada!

The monarch, in Canada, is a butterfly with orange wings, adorned with black veins. Each wing has a black border with aligned white dots. The wings, whose span is 93 to 105 cm, make this butterfly one of the largest species of diurnal butterflies in Quebec. The male differs from the female by the small black colored spots, located on the hind wings. Also, the black bands on the wings of the male are less thick than those of the female. Its yellow, white and black stripes are the characteristics of the monarch caterpillar. The caterpillars and larvae feed exclusively on milkweed, which is the only plant on which monarch butterflies can produce their eggs.

In the fall, the monarch butterflies of Quebec undertake a southward migration. Adults that overwinter in Mexico reproduce the following spring season and the females lay their eggs on the milkweed. Monarchs move north following the growth of this plant to arrive in Quebec in June. At this time, the females produce their eggs and the caterpillars appear three to twelve days later. They eat milkweed leaves for two weeks.

The caterpillar has a black filament composed of two identical parts. One part is close to his head while another near the tip of his abdomen. She stops feeding after molting 5 times. She then hangs under a leaf and metamorphoses into a green chrysalis. After fifteen days, the adult comes out of it. The butterfly is in a condition to fly away once its wings are dry and spread.

These butterflies breed in Quebec. Butterflies belonging to the next generation or the other, depending on the temperature, do not reach the stage of sexual maturity. They migrate to Mexico, where their wintering sites are located. The duration of winter rest continues until March. Females and males then complete their sexual maturation and unite for reproduction. Many males die out while most females take flight north. The latter produce their eggs on the spring shoots of the milkweed and die one after the other.

Monarch butterflies migrate, unlike most butterflies. During the fall season, monarch butterflies from Canada travel a long distance of about 4,000 kilometers to reach Mexico. The fall migration of monarch butterflies is an extraordinary phenomenon. Since they can't stand the harsh Canadian winter conditions, they move to the sacred fir forests otherwise known as oyamels located in central Mexico, to spend approximately six months there. While the population of monarchs from the southern region of British Columbia migrates to the coastal area of California.

In the spring season, the monarch returning to Canada undertakes a multigenerational migration. In other words, the generations of monarchs that return in the spring season are not the same as those that left in the fall. In certain circumstances, it is the great-great-grandchildren of monarch butterflies from the previous summer season that arrive in Canada.

The presence or absence of monarchs has an important significance on the development of environmental conditions. This animal species, like many other insects, provides pollination. As a pollinator, the monarch butterfly carries pollen from flowers. In 2023, the monarch butterfly is listed as a species at risk in Canada. It is also one of the common natural heritages between Mexico, the USA and Canada. Throughout North America, this butterfly is used to teach love and conservation of nature or to teach metamorphosis and biology.

The size of monarch populations in North America has experienced a significant decline in recent years. And the survival of this species is to be feared. The following factors are the main causes.

During the winter season, many monarchs live in small areas of the oyamel fir forest in central Mexico. We recognize this small region by its vulnerability to disease and extreme weather conditions. It is also subject to the risk of predation and vulnerable to fires. This geographical environment specific to the life of this animal species is also subject to degradation linked to forestry or agricultural exploitation as well as to the clearing of forests.

Changes in weather conditions are the main causes of long-term climate change. These negatively impact monarch butterflies. Frequently fast, gusty winds, often accompanied by thunderstorms, are likely to reduce forest habitat in Mexico. In addition, an intensification of wet and cool summers and springs in the United States and Canada decreases the growth rate of this animal species.

The increasing use of herbicides and insecticides in North America is associated with the decline of milkweed. This use also leads to a decrease in the number of plants, producing the nectar, which the monarch butterflies need for their immigration in the fall.

Usually, this animal species lays its eggs on milkweed. However, by mistake, females may lay their eggs on Vincetoxicum rossicum (Domestic venom from Russia). This invasive plant grows in southern Ontario and Quebec in Canada. If monarch butterfly larvae hatched on this plant, they have no chance of living

Another butterfly belonging to the family of Nymphalidae resemble the monarch butterfly. We are talking about the viceroy. The latter is characterized by the continuous black line on the veins of its hind wings. It is also distinguished by an alignment of black dots, which is less important than that of the monarch butterfly. The latter is taller than the viceroy.