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Flowers, Fruits, and Frass

What Gardeners Can do about the Monarch Population?

The recent news of the declining monarch colonies in Mexico has many Illinois gardeners and schoolchildren worrying about the impact here in Illinois. The butterflies, which spend the winter hibernating in the forests of Mexico, occupied only 1.65 acres in December 2013 –a 44 percent drop from 2012, according to a survey done by Mexico's Monarch Butterfly Biosphere Reserve.

Omar Vidal, director general of World Wildlife Fund of Mexico, told National Geographic, "The monarch butterfly as a species is not endangered. What is endangered is its migratory phenomenon from Canada to Mexico and back."

Migrating monarchs have had a tough time adapting to an ever-changing Illinois landscape. The milkweed that sustains the monarch caterpillars is beginning to disappear from the landscape because of the use of herbicides, reduction in natural areas and competition with invasive species. The drought in 2012 dried up most natural growing milkweeds and the wet spring of 2013 exposed caterpillars to deadly fungal pathogens.

In Mexico, freezing temperatures and heavy rains have further lowered the monarch population. Forests of oyamel firs in central Mexico have been fragmented and degraded for the past several years.

A once-fascinating phenomenon of the monarch migration spanning thousands of miles and multiple generations may be lost from Illinois without some human awareness and intervention.

One strategy would be planting milkweeds, not just one or two but fields or large drifts of the plant and multiple species. If you have even the smallest landscape or garden, a grouping of milkweed will not only be aesthetically beautiful and easy to take care but also may ensure your child gets to experience the hatching of the monarch from the chrysalis like you did when you were in third grade.

Several milkweed species can be planted and are native to the Central Illinois like swamp milkweed, whorled milkweed, prairie milkweed, common milkweed and butterfly milkweed. Even the southern milkweed species sold in greenhouses and garden centers as an annual can provide habitat for monarchs in Illinois.

Another strategy would be to be more accepting of weeds and limit your use of herbicides. Plants considered weeds, like milkweed, can be crucial to attracting native bee populations and used as larval plants for some of our favorite butterflies and moths.

Limiting your use of pesticides in the garden, landscape and on trees can be beneficial to the future population of monarchs. Never spray a plant that is in flower and visited by bees and butterflies.