Beautiful, orange-and-black monarch butterflies flitter from flower to flower, foraging for nectar each summer in the USA and southern Canada. The milkweed plant is vital to the life cycle and survival of the Monarch butterfly. It serves as the host plant through the monarch’s developmental phases and is the caterpillar’s sole food source. Common milkweed grows wild in fields, along rural roadsides, and in sandy coastal soil.
As milkweed plants have dwindled in abundance, so have the monarch population. In the past twenty years, there has been a 90 percent reduction in the US population of migrating monarch butterflies. The estimated population of 1 billion monarch butterflies wintering in Mexico has dropped to less than 50 million. The more we understand about the life cycle of this magnificent, migrating pollinator, the more we can do to help it regain a thriving presence.
Life Cycle of the Monarch Butterfly
There are four stages in the life of a monarch butterfly: egg, caterpillar, pupa, and adult. When the weather warms in the USA, adult monarch butterflies head north from their winter respite in the southern forests of Mexico. The monarchs return to the southern US in mid-March for breeding.
The adult female lays tiny eggs covered with a sticky substance on the underside of milkweed leaves. The caterpillar hatches from its egg several days later. The eggshell is the caterpillar’s first meal. From then on, the caterpillar thrives on milkweed leaves. The leaves of the milkweed plant are extremely bitter and toxic. The monarch caterpillar and adult butterfly retain the poison in its body, thus protecting it from being eaten by birds. In its first two weeks, the caterpillar increases in size by 2,700 times. As the caterpillar grows rapidly, its skin splits open; the caterpillar crawls out and continues to grow bigger. It repeats this process several more times. Nearly 80 percent of the food the caterpillar eats is stored and converted to fat in the abdomen, in its fat body. Once the caterpillar is mature, it stops eating.
The caterpillar weaves a silk pad on the underside of a twig and attaches itself. Hooked to the twig, it sheds its skin for the fifth time, revealing the pupa. Encased in a turquoise and gold chrysalis, the pupa remains attached to the twig for two to three weeks. At two weeks, the chrysalis becomes transparent, and eventually begins to crack open, allowing the butterfly to emerge.
Having been tightly folded within its chrysalis, the wings of the newly emerged monarch butterfly are initially soft and limp. As the wings unfold, fluid starts pumping through its veins and its wings stiffen. Monarch butterflies thrive on a liquid diet of nectar and water, as they cannot bite. They drink through a long tongue called a proboscis that works like an eyedropper drawing up nectar. Like a retractable garden hose, its tongue coils up under its lower lip when not in use. Monarchs smell with their antennae, and taste with their feet. Nectar and water are tasted by the sensory hairs on its legs and feet. Once detected, it uncoils its proboscis.
The monarch butterfly will continue to feed, fly, and reproduce throughout the US and southern Canada, for several generations. It is the fourth generation of monarch butterflies that migrates to Mexico in fall. Traveling as much as 100 miles a day during its 3,000-mile migration, the butterfly relies on the huge volume of food it ate and stored in its fat body as a caterpillar. The monarch butterfly’s fat body accounts for about one-third of its total weight when migrating. This stored energy source helps them survive through fall migration and winter dormancy in the fir forests of southern Mexico, until spring, when they fly north for spring breeding.
What can we do to help the monarch butterfly thrive?
The sharp decline of monarch butterflies put it at risk for becoming endangered. To save the monarch butterfly, the US Fish and Wildlife Service, the National Wildlife Federation, and the National Fish and Wildlife Foundation are working together to grow milkweed and other butterfly-friendly plants along the monarch’s main migration route from Minnesota south to Mexico. State parks in regions that once hosted thriving monarch populations are also planting milkweed seeds.
We can help too.
· Establish a wildflower garden in your yard for pollinating insects like the monarch butterfly and honeybee.
· If you see a caterpillar on a milkweed plant, do not remove or kill it.
· Ask your local government and garden clubs to work together to establish pollinator wildflower gardens in city parks, etc.
· Encourage local farmers to designate space along fence rows, and in ditches for native wildflowers to thrive, without the use of chemical sprays.
· Plant native wildflower species of milkweed in your yard or field. Common milkweed, butterflyweed, and swamp milkweed are ideal choices. You can collect seeds from an established plant, or purchase seeds or plants from a plant nursery or local garden center.
· Plant native wildflowers along your driveway and fencing.
· Don’t spray chemical herbicides on your lawn, garden, or fields.
· If your local electric authority sprays chemical herbicides under power lines on your property, contact them, complain and ask to be placed on the no-spray list.
· Buy a butterfly kit. Encourage your children to experience, and appreciate the life cycle of the butterfly, firsthand.
By Deborah Stafford Tukua, freelance writer and author of Traveling the Natchez Trace Parkway from A to Z.
Stay in touch, join our list at www.DeborahSTukua.com