Wednesday, February 16, 2011

Monarch Butterfly by Sarah Hurtado

The Danaus plexippus, more commonly known as the Monarch butterfly is a member of the phylum Arthopoda, the family Nymphalidae, and genus Danaus. It is the best known butterfly in North America. However, this butterfly is not confined only to North America. It has been found in New Zealand, Australia, the Canary Islands, the Azores, Madeira and may occasionally migrate to Western Europe. The butterfly has learned how to adapt to their environment through migration and also how to prevent themselves from being eaten.


The Monarch butterfly has a wingspan that ranges from 3.5-4 in. Their wings are a yellow-ish orange and the outside lining and veining is black with two repeated white dots along the outside of the wing. The male butterfly is slightly larger than the female and they also have a black patch of androconial scales on the hind wings. They have six legs, but only four are used because the front two are carried against their body. As an adult, the butterflies have a tube-like proboscis which serves as a “tongue” to drink nectar. The body is composed of three parts; the head, the thorax, and the abdomen. A single creamy white/ yellow egg weighs about .46 mg and is about 1.2mm long. The caterpillar has yellow, black, and white stripes and will reach a size of 2 in.
Form and Function:
The first meal for a caterpillar is its own shell! After it has eaten its shell, the caterpillar uses its mouth to eat the poisonous milkweed leaves to add the toxins produced by the plant to their bodies to poison their predators. The adult Monarch butterfly uses its proboscis to sip liquid food. The tongue like body part remains coiled when not used, and uncoils to sip the nectar from milkweed, dogbane, red clover, thistle, lantana, lilac, and goldenrod plants.
Excretion is important to the butterfly for the same reason it is important to other animals, to remove unwanted substances. Excretion is a way of assuring that the levels of salt and water in the haemolymph, or the blood of the butterfly, remain consistant. Toxic compounds are produced during metabolism and excretion is a way to cleanse the system. The Monarchs use a system of tubes called Malpighian tubules, which are found throughout their bodies. The job of these tubules is to pick up materials from the haemolymph and carry them to the rectum of the butterfly. The unnecessary or harmful materials are released in a liquid form.
The reproduction cycle of a Monarch butterfly begins with a mating period that begins in the spring before the migration from winter states. Courtship is separated into two different stages, the aerial and ground phases. During the aerial phase the male pursues, nudges, and then essentially takes down the female. During the ground phase, copulation occurs. The male and female remain attached for up to 60 minutes. A spermatophore is transferred into the female. The speratophore also supplies the female with energy which helps her in carrying out the reproduction process while migrating. The life cycle includes a complete change of form called metamorphosis. First the female lays the eggs during spring and summer. Second, the eggs hatch after four days, and caterpillars are revealed! They feed on their casings then on milkweed with the intention to store fat for energy which will carry them through their non-feeding pupa stage. They remain a caterpillar for only about two weeks before entering the next stage. The third stage they enter is pupa or chrysalis stage. The caterpillar spins a silk sac on a stick or leaf and hangs from the silk pad. It hangs upside down and eventually molts but leaving itself encased in a green exoskeleton. Hormonal changes then occur which is the next step to becoming a butterfly. The fourth and final stage includes the butterfly emerging from the chrysalis where it must stay for a few hours until its wings are dry. During this waiting period, fluid is pumped through the weak wings to assure that they are stable, after this the butterfly flutters its wings and feeds on milkweed and other plants.
The best protection the butterfly has are their ancestors! The Monarch is a poisonous butterfly that first gets its poison, cardenolide glycosides, when it is a caterpillar after eating the milkweed plant. Predators, mostly birds like Jays and Orioles, become very sick from the poison and remember the bright orange color of the butterfly and avoid all Monarchs in the future!
Impact on the World and Humanity:
Sanctuaries have been created at certain migrating locations to attract the beautiful butterfly which generates a significant amount of tourists. The butterfly is also used by many schools and educational programs to study the life cycle as well. Many organizations have identification tagging programs to better understand the migration of these insects. Plastic stickers containing identification information is place on the wing of the insect. They are also enjoyed by gardeners who are burdened by milkweed plants.
Journal Article and Review:
This article is about a research team in the United States that researched the ability of the Monarch butterfly to use medicinal plants to fight a parasite. They have found that some species of milkweed, the Monarchs main food source, can reduce parasite infection. They also found that females lay their eggs on plants that will make their offspring less sick, which proves that they have evolved the ability to medicate their offspring. The fact that butterflies can use plants for medicinal purposes, give scientists hope that there could be cures for humans in plants as well.
Brady, Initials. (n.d.). The monarch butterfly. Retrieved from

Monarchs (butterfly. Wikipedia. Retrieved February 16, 2011, from

Oberhauser, K. (n.d.). Anatomy/characteristics of monarchs. Retrieved from

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