Metamorphosis: The Monarch Butterfly Life Cycle
After mating, the female Monarch lays her eggs and then dies. She only lays her eggs on milkweed plants. Milkweed is the only host plant for Monarch butterfly caterpillars. She will usually only lay one egg per plant, in order to have sufficient food for her babies to survive. She is capable of laying up to 400 eggs. She attaches her pin sized eggs to the underside of the milkweed leaves. The eggs are attached with a waterproof type glue.
In 3-4 days, the egg will hatch. The tiny, 1/8″ long caterpillar will eat its shell and then begin eating milkweed leaves. At first, the tiny caterpillar only eats a small amount. Within a two week time frame, it will have eaten at least 20 full sized milkweed leaves. The caterpillar stops to rest and shed its skin 5 times. It will often eat its own skin. These molting periods are called instars.
At the end of 2 weeks, the caterpillar has grown to about 2 inches. The large caterpillar begins looking for something to hang from and pupate on. It will climb on a stick or some other type of plant. It usually does not pupate on the milkweed plant.
First the caterpillar makes a silk pad with its mouth. It then attaches its rear prologs to the silk pad and hangs in a “J” formation until the next day. It does what appears to be sit-ups on several different occasions while in the “J” formation.
The next day, the caterpillar begins to pupate (turns into a chrysalis). Its once vibrant antennae become limp, its head detaches and the skin splits from the back of the head and wiggles all the way up to the top of the cremaster (the point where it is attached to the silk pad). Underneath its skin is a lime green and yellow colored chrysalis. It wiggles for a while and throws off its skin and then the chrysalis dries and hardens.
In 1-2 weeks, the chrysalis will crack open and a crumpled adult Monarch butterfly will emerge. It will hang while blood rushes through its veins. The wings will drip a fluid as they begin to harden. After about 3-4 hours, the adult Monarch butterfly will be able to fly away, or nectar on flowers. The process of changing from an egg, to larva (caterpillar), to pupa (chrysalis) to butterfly is called metamorphosis. The female adult butterfly will nectar on flowers, or old rotten fruit, mate, fly north or south depending on the migration cycle, lay eggs, and then die.
Loss Of Habitat
Milkweed is the only plant the Monarch caterpillar eats, or that the Monarch butterfly will lay her eggs on. Due to pesticides and farming, milkweed has been on the decline. With no milkweed, you have no Monarch butterflies. You can help the Monarch butterflies by planting milkweed in your garden and reducing or eliminating pesticides in your yard and garden. Monarchs follow the milkweed paths during migration. If you plant it, they will come!