Thursday, July 13, 2017

The Plight of the Monarch

The Plight of the Monarch

     In a world filled with amazing animals, one tiny but colorful insect stands out because of its endurance and unique life cycle. Weighing only .0095 to .026 oz with a lifespan of 6 to 8 months, the amazing monarch butterfly manages to journey up to 3,000 miles on paper thin wings through storms and across vast landscapes. Although monarchs are found throughout the world, the North American monarch is referenced here. The perilous journey of the North American monarch is necessary as the milkweed is only found in the midwestern US and Canada in the summer and the monarch cannot withstand cold winter temperatures. Thus, the need to migrate between winter locations in Mexico or warm areas of southern California and the summer feeding areas of the US and southern Canada.

      Unfortunately, populations of the brightly colored monarch butterflies have gone into a steep decline. Understanding more about their life cycle and habits is key so that humans can help to reverse this trend.

     Monarchs begin their life as eggs which are placed on milkweed plants. The placement of eggs on milkweed is vital for monarchs as the larva, otherwise known as a caterpillar, which hatches from the eggs feeds almost exclusively on milkweed. This is only the beginning of the most unusual life cycle over the next year.

      The young caterpillars feed voraciously on the milkweed and are capable of consuming an entire leaf in 5 minutes.  To protect from being eaten by lizards, frogs and birds the caterpillars produce a toxin from the sap of the milkweed which is poisonous to potential predators. The brightly colored caterpillar serves as a warning to predators.

     This first phase, also known as an instar, may only last a few weeks before the caterpillar begins one of the most incredible transformations in nature. The larva while attached by a thin thread to a stationary object will next spin a protective case or chrysalis inside of which the caterpillar will undergo a metamorphosis into the beautiful and iconic monarch butterfly.  This second generation will only live for a short while during which they will continue to feed on milkweed and later on nectar after another metamorphosis into a butterfly as they flutter further north. Soon, this generation will lay eggs on milkweed which will begin the third generation of butterflies.

     As the summer begins to wane, this third generation of the year will again cycle through the stages of egg to caterpillar to butterfly.  The fourth and final generation of the monarch which emerges in September to October is the long distance flier to winter ranges in California or Mexico ahead of the advancing winter. One of the truly amazing feats is that although this generation of monarchs has never been to the winter retreat, they manage to return to the same area and often to the same tree as the butterflies from the previous winter.

    This perilous journey of thousands of miles is full of obstacles to survival along the way. Recent changes in farming practices have lead to a steep decline in milkweed throughout the corn belt in the midwestern US. The population and extent of milkweed necessary for the caterpillars has declined because of the conversion of areas that previously grew milkweed to corn for ethanol and because the increased use of herbicide resistant crop species has allowed the use of non-selective herbicides which kills the milkweed. Illegal logging has impacted winter habitat in Mexico and recent unprecedented weather events may have adversely impacted the delicate butterfly.

   What can be done to reverse this recent trend? Preserving a corridor of milkweed is absolutely essential to providing a food source for the larval stage of the monarch. Conserving areas that can grow milkweed, especially in regions dominated by managed crops, will provide feeding stations along the northward path.

      Conservation of habitat within areas of historical wintering retreats in  Mexico and California is essential. Perhaps ecotourism in these areas will provide an additional financial incentive to preserve these critical areas. Small landowners and even urban dwellers can encourage milkweed or nectar producing plants on their properties. Finally, education that helps to raise awareness of the plight of the monarch will encourage people to care so that future generations can also enjoy the amazing monarch.

Here are some additional sources of information:

Battle For Butterflies

Habitat Highways 

Monarch Butterfly

On the Track of the Monarch Butterfly