Monarch Butterfly Life Cycles

Butterflies develop through a process called complete metamorphosis, during which there are four distinct stages of life. These stages begin most commonly on the milkweed plant, a toxic perennial that makes the Monarch butterfly poisonous to predators. The entire process, from egg to adult, takes about a month to complete. During the stages of its life cycle, the Monarch butterfly undergoes extreme and beautiful changes.

  1. Egg

    • The Monarch butterfly begins life as most insects do---contained in a solid eggshell, protected from the outside world. Around March or April, female Monarchs begin laying eggs. They lay a single egg on a milkweed leaf. The egg measures about one mm tall and .9 mm wide. After about four days, the egg will hatch into a butterfly larva, or caterpillar.

    Larvae

    • The Monarch caterpillar grows and develops through five stages called instars, or the periods between molting. When the larva hatches from the egg, it is a creamy colored caterpillar with two large eyes on one end. Its first meal is the shed egg sac from which it hatched. Afterward, the caterpillar will dine on the leaves of the milkweed. As the larva grows, it gets too big for its skin and sheds it. The caterpillar will eat this skin and subsequent shed skins until it forms its chrysalis. By the second instar, the larva begins to resemble the common black, gold, and white banded Monarch caterpillar. At this stage of its life, the caterpillar has two sets of sensory antennae located at both ends of its body. The larvae will grow from two to six mm and reach 25 to 45 mm in length. The entire process lasts roughly two weeks. The caterpillar will then seek out a safe shelter to spin a chrysalis.

    Pupa or Chrysalis

    • The pupa stage of the Monarch's life is possibly the most exciting of all. During this stage, the Monarch caterpillar will undergo astounding physical changes to become the easily recognizable Monarch butterfly. The caterpillar will use the silk spun from its spinnerets, located at the back of its body, to attach its hind legs to a limb. Then it spins a greenish-blue chrysalis around its body. It remains in the chrysalis for 10 to 14 days. The chrysalis will become transparent a day before it hatches, releasing the now adult butterfly.

    Adult Butterfly

    • At first, the Monarch's wings are soft and damp. By pumping fluid into its wing veins, the butterfly will dry and expand the wings into the beautiful and brilliantly colored wings we associate with Monarch butterflies. Males have slightly thinner wing veins than the females and have an indentifying black spot on the hind wings. Males are also smaller than females and lighter in color. Adult Monarch butterflies only live between two and six weeks. They spend their time eating, and then they will seek out a mate, lay eggs and die. While Monarch butterflies can be seen year-round, there are actually four separate generations of butterflies born in one year. What makes the monarch butterfly remarkable is the last generation. Unlike the previous generations, the fourth generation adult butterflies travel south to warmer regions, where they live for six to eight months. They will spend the months hibernating until February or March. At that time, the fourth generation adult monarchs fly north to seek out a mate. They then lay their eggs and, exhausted and torn from the long migration north, they will finally die, thus beginning the new generation of monarch butterflies.