The Life Cycle of Monarch Butterflies and the Annual Migration
An amazing life cycle of monarch butterflies shows the beauty and the perfection of nature. Some insects have a complete metamorphosis which is a changing in the insect body form through different stages. Monarch butterfly undergoes a perfect complete metamorphosis process: egg, larva, pupa and adult (Bernstein, 1990). The process of metamorphosis is guided by genes.
There are three hormones produced from the genes.First, Brain hormone which makes a gland in the thorax gives the second hormone (Molting hormone) which is completely depends on the third hormone (Juvenile hormone) which causes the molting of the larva when it presents in high amount. Each stage of the metamorphosis is specialized to do a particular activity so the metamorphosis process is very beneficial in that manner because it prevents a mixing between two functions that ask for huge energy such as in the caterpillar stage the mission is growing while in the butterfly stage responsible for the reproducting (Towle, 1991).
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After mating, the male lepidopteran dies while the female has to survive until she lays her eggs. She chooses the place to put her eggs carefully by choosing a close spot to leaves so that the caterpillars can eat when they hatch . The mission of the caterpillar is eating.
Starting with it shell which protected it as it developed . When the caterpillar grows, its ready to move to the next stage (pupa) by spinning a silk pad and hanging their heads downward from the pad . here are active changes inside the pupa to form an adult butterfly by completing the transformation of the organs and the arrangement of the muscular system then after a while its ready to emerge (Patent, 1979). Monarch butterflies migration Migration of monarch butterflies is the most amazing biological event on the earth. The journey of monarch butterflies is around 3100 miles (500 km). When the temperature drops in winter in the north of the U. S.
, butterflies migrate to the south (Mexico and California) looking for warmer places (Hussong, 2010).The annual migration needs four generations to be complete. All the four generations have the same time limits of the first three stages of the life cycle: four days as an egg, two weeks as a larva, and ten days as a pupa but the difference comes in the last stage “as an adult” the first generations live for (2 – 6) weeks but the fourth generation lives for (6 – 8) months in Mexico and California then its migrate north lay their eggs and die (Rosenblatt, 2002). The threats to monarch butterflies The annual migration of monarch butterflies is facing several threats.The most dangerous threat that affects the migration is deforestation. An illegal logging caused by the Mexicans is the major factor of deforestation in Mexico. Now with a decreased number of trees monarch butterflies lost their favored spots and they have less area to settle.
Some scientists say that the entire extraordinary migration of the monarch butterfly is in danger of collapsing. Global warming is important as well because it’s causing a decrease in the number of monarch butterflies. Climate change is affecting their wintering grounds and summer breeding grounds.A wetter, colder weather is predicted in Mexico over next 50 years and the freezing temperature with rain can be deadly to overwintering butterflies. The government and the authorities in North America are trying to save monarch butterflies by building sanctuaries and supporting monarch butterflies organizations such as: Monarch butterfly biosphere reserve, and North America Monarch Conservation Plan (NAMCP).References Bernstein, L. (1990).
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