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College of Food, Agricultural, and Environmental Sciences


Ohio Experiencing Population Explosion of Red Admiral Butterflies

August 7, 2001

COLUMBUS, Ohio - State lepidopterists are seeing a population explosion of red admirals, the first time in 15 years the butterflies have been so widespread.

The Ohio Lepidopterists' last complete statewide red admiral observation figure was in 1999 with less than 50 butterflies counted. Butterfly monitors, who have continuously monitored two Lake County sites since 1996, have already recorded over 190 red admiral butterflies this summer, over five times as many as the previous year in the same area. Observers have also reported high red admiral numbers throughout the state, as well as the entire midwest region. For example, an observer in Franklin County reported seeing over 300 red admirals at Blacklick Woods Metro Park in one month.

Barb Bloetscher, an Ohio State University entomologist, said officials are unsure why red admiral numbers are so high, but speculate that the exceptionally snowy winter may have helped the over-wintering butterflies survive till spring. "Ordinarily we don't have many butterflies that over-winter here. But we had a lot of snow this past year that may have provided enough insulation for the butterflies that did over-winter to survive," said Bloetscher. "Southern states like Kentucky and Tennessee have also reported good red admiral numbers, and the butterflies always tend to migrate north." Though not as popular as other butterflies, like the Monarch, observers are excited over the high red admiral numbers from an aesthetic, as well as an environmental standpoint. "Well, the butterflies, for one thing are very pretty to look at," said Bloetscher. "But they are also considered a beneficial butterfly, as they eat weeds. They are not considered pests, like other butterflies, such as the American painted lady which has a tendency to feed on herbaceous ornamental plants." The red admiral has been observed in nearly every Ohio county, and is characterized by its fast and erratic flight. The species is recognized by longitudinal red bands along its dorsal hindwings, and horizontal red bands and white spots on its dorsal forewings. Nettles are the primary host plants for the butterfly and the species can be found along forest margins, roads, open fields, wetlands, parks, gardens and orchards.

The red admiral is currently in its second-generation life cycle. The species will begin to migrate south this month. "Some butterflies will stay throughout the winter," said Bloetscher. "But most will migrate south and if they make it through next year, we could have another good crop coming through Ohio."

Candace Pollock
Barb Bloetscher