Monarchs will soon leave for Mexico

By University of Illinois Extension — Boone, DeKalb and Ogle Counties

The monarch butterfly is one of the most recognizable insects in Illinois. In 1975, it officially became our state insect, thanks to a class of elementary students in Decatur, Ill.

Actually, many states recognize the monarch as either their state insect or butterfly. People often separate butterflies from their other insect counterparts. It is no wonder, as butterflies, and specifically our precious monarch, are held in such high regard. The monarch is beautiful, graceful and capable of migrating to a warmer climate to sustain the species.

Butterflies go through complete metamorphosis. This means there are four stages to the life cycle. The adult lays an egg on milkweed, which is the specific host plant for the monarch. The egg hatches after three to four days, and the larva, which we often refer to as a caterpillar, then begins a two-week feast on the host plant and shedding its skin, or molting, five separate times. Each molting is referred to as an “instar.”

The caterpillar, or larva, is quite large by the time it reaches the fifth instar and travels off the host plant to another location. It then makes a silk pad to hold on to during the final molt, leading into the pupa stage for 10 to 14 days. This is called a chrysalis. Peggy Doty, University of Illinois Extension educator, reminds us, “If we were discussing moths, this pupa stage would be called a cocoon.” The pupa leads to the completion of the life cycle, and the adult monarch emerges. The complete metamorphosis of the monarch takes approximately 30 days to complete.

The last monarchs of the summer leave around October and head south to the mountains of central Mexico. The monarchs you will see in early spring will not be these monarchs, but the offspring of our fall migrants.

When the monarchs migrate back north, they lay eggs in the southern United States as they travel. The adults actually expire before they reach Illinois. It is their children and often their grandchildren who have completed the journey back home.

These offspring are the monarchs you encounter in your gardens in the spring. They will lay eggs, and the cycle will continue all summer until the last ones emerge and fly south again.

It would obviously be more adventurous for the late monarch as it gets to travel and vacation in Mexico,” said Doty.

In 1991, central Mexico experienced severe weather with storms and very low temperatures,” Doty added. “A large number of the migrant monarch population was blown to the ground and died of what we would call hypothermia due to being wet and cold. Interesting enough, as they shoveled up the piles of monarchs, those on the bottom were still alive, being insulated by the others.”

Monarchs are tagged with tiny wing tags so scientists can track them and note any changes. The purpose for collecting all those dead butterflies was to identify any of those with tags. Some scientists feel we have yet to see the numbers of monarchs we had prior to this devastating event.

You can do simple things to help our monarchs continue to rebuild their population. Plant a butterfly garden filled with host-specific plants, which supply food for the larva and nectar for the adults. Create a safe watering area for your butterflies by wetting open soil areas each day or putting water and pea gravel in a shallow dish with the water level just below the gravel.

Butterflies do not want anything to do with open or moving water,” Doty said. “It would help the monarchs tremendously if we would encourage milkweed to grow in our yards or gardens, as it is the only plant the monarch will use to lay her eggs, and it is the only food the larva will eat.”

University of Illinois Extension will be offering a spring butterfly and hummingbird gardening class. Watch for this and other interesting workshops at Extension’s website by going to

For more about the migration of monarchs, go to Monarch Watch at

From the Oct. 3-9, 2012, issue

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