Monarch Butterfly

The monarch butterfly, as known as Danaus plexippus, is often called the milkweed butterfly because its larvae eat the milkweed plant. They are also sometimes called "royalty butterflies" because their family name comes from the daughter of Danaus, ruler of Argos. There are many other interesting facts about this butterfly including its anatomy and life cycle, where the butterfly lies on the food chain, the migration from Canada to Mexico, why the butterfly is being threatened, and lastly, what is being done to help the butterfly.

The anatomy of the monarch starts with it coloring. The monarch butterfly is bright orange with a white spots in a black margin around the edges. The veins on the wings are also black. The caterpillar is ringed with yellow, black, and white on each segment and has a pair of black fleshy tubercles at each end (Emmel, 1999). Monarchs smell with their antennae while they taste with their feet (Wexler, 1994). While the male monarchs have scent scales on their wings and "hair pencils" on their abdomens which secrete a scent (Emmel, 1999). The male scent is used during mating. The copulation of a male and female monarch can last from thirty to sixty minutes which is about average for most butterflies (Emmel, 1999).

The life cycle starts as larva or caterpillar. First, the monarch lays the eggs on the milkweed plants. Next, the egg hatch into a caterpillar. The caterpillar then eats the milkweed plants until they are large enough to pupate (Emmel, 1999). Then, the caterpillar attaches a pad of silk to a stem of a milkweed plant so it can hang while it transform into a butterfly. Next, the caterpillar sheds it larval skin to reveal the chrysalis inside (Emmel, 1999). After it shed its skin, the pupa hardens and the chrysalis earns it name by glowing in the sun. As the pupa stage comes to an end, the butterfly can be seen through its pupa shell. The monarch emerges by splitting the pupa along the length of it proboscis (Emmel, 1999). First the legs emerge. Then the fluid fill body pumps its fluid into the veins of the wings while the body shrinks to normal size. Finally, the butterfly hangs from the pupa about two hours while the wings dry (Emmel, 1999).

Monarchs do not have many predators expect for man. The monarch's trick to not being eating it two hold. First, the coloring of the monarch mimics that of a wasp or a bee which makes predators think twice before trying to eat them. Second, the milkweed plant in which the caterpillar eats has toxins which make the wings of the butterfly distasteful to predators. The monarch butterfly drinks nectar while the caterpillar eats the milkweed. The monarch favorite food here in Florida is Asclepias ssp. or milkweed (Wexler, 1994).

The migrating of monarch is because of the harsh conditions on the northern US. They move south from areas of southern Canada and most of the US to a few sites in Mexico (Grzimek's, 2003). They migrate itself usually takes three to four generations of monarchs (Clattenburg, 2004). Scientists do not know why they migrate, but there are different theories. The first theory is the change of light in fall (Clattenburg, 2004). While others scientists claim the monarchs have a chemical in their bodies in which they are attracted to Mexico where the congregate in certain trees (Clattenburg, 2004). The latter does not explain why monarchs stay in Southern Florida as permanent residents (Emmel, 1999).

Three different things are endangering the monarch butterfly. First, is the deforestation of Mexico. Through illegal logging of the forests and the thinning of the canopy the monarchs are left vulnerable to the elements including frost and freezing rain (Wexler, 2004). Second, is a genetically engineered corn. The corn is engineered to be insect resistant which when the milkweed plant grows on the edges of the fields, the studies have shown