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BUTTERFLIES OF THE AMERICAN PRAIRIE VIGNETTE
by Doug Taron, Peggy Notebaert Nature Museum
June 23, 2012
Photo by Dan Huske
Doug presented stunning digital images of some of the rarest and most beautiful butterflies known to our geographic region photographed in their unique habitats or on the leaves of their host plants.
Doug explained that butterflies are found in all the major ecosystems of our region including prairies, wetlands, forests, savannas, sand dunes and fens, as well as in urbanized landscapes.
His stunning photos of rare butterfly species included Black tiger swallowtail, Red Admiral, Buck-eye, Clouded sulphur, Eastern tail blue, Gorgon checkerspot, dusty skipper, Silver spotted skipper, American copper, Hoary elfin, Olympia marvel, Silver boardered fritillary, Viceroy, Baltimore checkerspot, two-spot skipper, black dash skipper, Karner blue (federally endangered species), Silvery blue, Yellow tiger swallowtail, Pearly eye, Question mark butterfly, Swamp meadow mark, Orange sulphur, Great spangled fritillary, Aphrodite fritillary, Regal fritillary (threatened) and Regular painted lady.
Photo by Dan Huske
Doug spoke at length about the fascinating life cycle of the magnificent Monarch butterfly and the remarkable migration of individual monarchs to their wintering grounds to the forests of Mexico each autumn. This is only possible because the Monarch breeding cycle goes into dormancy during the southward migration. However, the breeding cycle resumes when the return migration begins. It takes two individuals and two breeding cycles on the return trip from Mexico before Monarchs reach their northerly range. Monarch butterflies are dependent upon all milkweed species as host plants for their survival. Doug informed the group that Monarchs are doing well here but their wintering grounds in Mexico are in peril because their forested habitats are being lost to timber cutting.
Doug explained that all species of butterflies carry out their life cycles in very specific ecosystems ideally suited to ensure their survival and the propagation of their young.
Doug mentioned several butterfly host plants which include cherry trees, swamp thistle (found in fens), clover, garlic mustard, Timothy grass, sheep sorrel, prairie bearberry, sand cress, pale purple coneflower, little bluestem, violets, arrow leaf violet, willow trees, turtlehead, mullen, foxglove, blue joint grass, sedges, lupine, veiny pea, Queen Anne's lace, fowl manna grass and many more. Butterflies feed on tree sap, overripe fruit and prairie flower nectar, preferring sugary food sources.
One of the reasons certain species of butterflies may be in decline in our region is as a result of the intensive use of lawn herbicides which eliminate clover and other weedy or grassy species needed by certain butterflies as habitat and host species. However in some places, grasses and other plants grow where lawn mowers do not reach under or near fences and provide little edges of butterfly habitat in the middle of urban landscapes. Two-thirds of butterfly species live today in human dominated landscapes. Of the l09 species of butterflies of our region, 70% are urban species finding common weeds as host plants.
While prairie plants represent only 20% of total species diversity, 50% of the majority of species are animals, fish, birds, vertebrates and invertebrates. However, invertebrates including butterflies and insects, comprise 64% biomass of all species within the majority of species.
Doug explained how to tell the difference between moths and butterflies. Moths have thin filaments at the ends of their antennae. Butterflies have little clubs at the ends of their antennae. Butterflies also have scaly wings.
Butterfly mating occurs in ecosystems most receptive to each species as females are typically ready to lay eggs on host plants one day after mating. Eggs are laid on the underside of leaves. Caterpillars hatch from tiny almost invisible eggs and rapidly become furry caterpillars with voracious appetites. Everything they need to survive and grow at this phase of their lives is provided by the leaves of their host plants.
Adult butterflies are successfully adapted to avoid predators. However, young butterfly caterpillars are most vulnerable and can be attacked and killed by multiple parasites and wasps which lay their eggs inside the caterpillars. They are also vulnerable to prolonged cold and wet springs, fungus infections and disease.
The skeleton of the caterpillar is outside of its body. The inside of the caterpillar holds the internal organs. When in the chrysalis phase of life, cell division occurs rapidly. When the butterfly is fully formed, the chrysalis splits open and the butterfly emerges to begin the mating cycle again.
Each butterfly species has its own migratory pattern and season. For example, Red Admirals migrate northward from the southeast. A sighting of an estimated 300 million Red Admirals was recently recorded in the spring. Butterflies cannot typically survive winters in cold regions.
Photo by Valerie Spale
Doug led the group on a Wolf Road Prairie walk following his presentation. Doug found good habitat and host plants along the wetland edge and speculated that rare wetland butterflies might be discovered here.
Monitoring populations of specific butterfly species provides critical information about the status of biodiversity in the Chicago Wilderness area and provides base line data on the numbers and health of our native butterflies.
For more information about the Judy Istock Butterfly Haven and the Chicago Academy of Sciences' Peggy Notebaert Nature Museum go to www.chias.org
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