Insects > Monarch Butterflies >Monarchs Are Lovely, but Poisonous.

Monarchs Are Lovely, but Poisonous.

The monarch butterfly is a beautiful flying insect with its large scaly wings. The bright colors on its body are so clearly visible that we feel they can easily attract the predators, but in contrast, this color helps the predators to distinguish the Monarchs from the other butterflies. It is because, the Monarch is not only lovely in appearance, but too toxic and poisonous, which is why the predators avoid eating Monarchs. Studies say, the foul taste of Monarch keeps the predators away and the bright color is a warning to the predators about the poisonous characteristic of Monarchs It is a common poisonous butterfly which eats poisonous milkweed in their larval stage. It lays its eggs on the milkweed plant. The bright orange and black color make monarch butterfly easy to see in the sky. Like other insects, butterflies have six jointed legs, a pair of antennae, 3 body parts and an exoskeleton. The three body parts are the chest (thorax), the tail end (abdomen) and the head. The six legs and the four wings of monarch are attached to the thorax. The thorax makes the wings and legs move because it contains muscle. The monarch butterflies are well known for the incredible mass migration that carries millions of them to Mexico and California each winter season.


The name “monarch” was derived in honor of King William III of England. Originally, the monarch was described in 1758 by Linnaeus.

Life Cycle

The life cycle of the monarch butterflies depends upon the climate conditions of the place where they bred.

Eggs- The monarch butterfly starts its life as a ridged, spherical egg of an inch long. On the underside of the milkweed leaves, the eggs of the butterfly are always laid singly. With quick drying glue, the female butterfly attaches its eggs to the leaf. The egg hatches in about 3 to 5 days and a small Wormlike larva also emerges.

Caterpillar- The caterpillar (Larvae) hatches from its eggs and eats it. Then, constantly it eats milkweed leaves. At this stage, the Monarch larvae turn toxic, by ingesting ‘cardenolides’ (Wiki _ Cardenolides is a type of steroid. Many plants contain derivatives, collectively known as cardenolides) present in the milkweed plants. After it transforms into a butterfly, the steroid shifts to different parts of the body, and mainly to the wings and abdomen.  The caterpillar grows; it loses its skin four times. It eats its old skin after each molt. It will stop eating when the larva is about 5 cm long and finds a place to pupate.

Pupa- The caterpillar turns into a pupa and it remains in it for about 10 to 14 days. From its spinneret, the caterpillar spins silk. The pupa attaches its hind end to a branch with small hooks and the silk in the anal prolegs. The monarch butterfly takes the form of jade green chrysalis, when the newly exposed skin dries and hardens. That time, it hangs down and molts for the last time. During this stage of life cycle, the caterpillar turns into a butterfly. Its whole body is recognized. The chrysalis becomes transparent in about 10 to 12 days and a damp butterfly rapidly emerges.

Adult- From the chrysalis, a beautiful but damp adult emerges with bright orange and black wing, veins and outer margins. On outer margins, its wings have white spots. And on the top of the Forewings, it has three orange patches. To inflate, the monarch butterfly then pumps, liquid in the wing veins. Its hind wings are rounded in shape and are lighter in color as compared to the fore wings. During the adult stage, there is no growth of the butterfly. It can eat only liquids, which it does through the proboscis. This adult monarch butterfly will continue the cycle by reproducing.


Monarchs Are Lovely, but Poisonous. Monarch Butterfly Eggs on Swan Plant - Photo by: Armon.

The monarch caterpillar’s first diet is its own eggshell. After that, it eats the poisonous milkweed leaves. They eat these leaves to integrate the milkweed toxins into their body in order to poison their predators. Milkweed is a poisonous plant which contains toxins.

The monarch butterfly is poisonous and the animals that eat it get very sick and vomit. Generally, it does not cause death, but it is harmful. These animals remember these brightly colored butterflies that they will avoid it in future. The monarch butterfly gets this poison in the caterpillar stage. Due to the presence of Cardinolide Aglycones in their body, the monarch butterflies are poisonous and foul tasting.


During the months between August and October, some groups of monarch butterflies migrate for over 2,000 miles. These butterflies fly from the USA and Canada to overwinter in the coastal Southern California to the Tran volcanic mountains of central Mexico. Along the migratory routes, female butterflies lay their eggs. This migration takes up to three generations of monarchs. The eastern population of monarch butterflies migrates from both south and north on a yearly basis. The eastern population of the Rocky Mountains migrates to the sanctuaries of the Mariposa Monarch Biosphere Reserve in Mexico.


Monarch butterflies are found all around the world in tropical and sub-tropical regions. They are found in all habitats like fields, meadows, cleared roadside and marshes. They live through most of the USA, Central America, Southern Canada,  mostly in Southern America, Mediterranean countries, Australia, the Canary Islands, Indonesia, Hawaii and many other Islands of Pacific.

Life Span

An adult monarch butterfly takes a month to develop. The life span of a monarch butterfly varies. It depends on the season in which it emerged from the pupa and it also depends on the migratory groups of the monarchs. Adults which emerge in the early summer season have a shorter life span and they live for about 2 to 5 weeks only. Those butterflies, which emerged in the late summer season, live over the winter months. The migrating monarch butterflies, that emerge in the late summer season from the pupa and then migrate south, live a much longer life of about 8 to 9 months.

The monarch butterfly is the state insect of the Idaho, Illinois, Alabama, Texas, West Virginia, Minnesota and Vermont. In the year 1990, it was nominated as the national insect of the United States, but the legislation did not pass.. The Centre of biological diversity, the Xerces Society and the Centre of food safety have filed an appeal to the United States Department of the Interior to protect the Monarch butterflies by having it declared as an endangered species. On 20 June 2014, the President of the United States Mr. Barack Obama issued a presidential memorandum entitled “Creating a federal strategy to promote the health of honey bees and other pollinators”. Sanctuaries and reserves have also been created in the California and Mexico at over wintering locations to limit habitat destruction. Monarchs are also used in nature centers and schools for the educational purpose.

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