A Habitat for Monarchs

"Planting a mix of native butterfly weed and annual tropical milkweed was a winning pollinator garden combination for our small 4-H Garden plot planted this summer," says University of Illinois Horticulture Educator, Kelly Allsup. The combination resulted in an explosion of monarch caterpillars. Hundreds of monarch caterpillars started their journey in our hundred square foot garden surrounded by a concrete parking lot. Egg laying by the adult monarch butterflies was not deterred by an early infestation of yellow aphids which was quickly managed by lady bugs and hover fly larvae.

The tropical milkweed leaves (Asclepias currassavica), especially, were devoured and stripped by the caterpillars, forcing the gardeners to trim them back. University of Illinois Extension Entomologist, Phil Nixon observed in his own garden and elsewhere that monarch caterpillars prefer the tropical milkweed over the native milkweed we grow here in Illinois. Other gardeners have seen the opposite effect, monarchs preferring native milkweeds. Nixon's gardening endeavors squash the claim that planting tropical milkweed in the Midwest will somehow interrupt the great migration south. Three factors cause monarchs to migrate: a steady decrease in temperatures, a steady decrease in the length of the day, and the quality of the milkweed. Like Nixon, our tropical milkweed has grown back and shows no signs of feeding or late egg laying. However, the flowers are still being visited by adult butterflies nectaring for their long journey.

Many caterpillars chose to form their vivid green and gold pupae perched on the concrete sign in the middle of the pollinator garden and some chose to crawl across the driveway to adorn the window sills, tree branches and large rocks on the north wall. It was quite a sight for people who only thought the garden was ornamental. Other flowering annuals like lantana, ageratum and native perennials like anise hyssop, liatris, lead plant, foxglove beardstounge, culvers root, coneflower, golden alexander and wild indigo were added to lure pollinators as a source of nectar. In addition, some of these plants, like the milkweed, serve as larvae hosts for native butterflies. For instance, golden alexander leaves are eaten by black swallowtail caterpillars and wild indigo feeds the larvae of five butterflies: wild indigo duskywing, hoary edge, frosted elfin, marine blue and orange sulphur. For more information on pollinator associations for your native garden plants visit the website www.illinoiswildflowers.info.

The inspiration for the garden came from a Pollinator Pocket program in Champaign where easy to replicate designs are made available on their website at http://web.extension.illinois.edu/cfiv/pollinators/. Future plans for our small

pollinator garden include planting spring flowering bulbs, incorporating more fall bloomers, a pollinator tracking workshop and building an insect hotel.

For more information contact Kelly Allsup, Extension unit educator, Horticulture-Livingston, McLean and Woodford Unit at (309) 663-8306, or kallsup@illinois.edu.