Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
5/29/03
FOR IMMEDIATE RELEASE
Contacts:
Mary Harris, Reiman Gardens, (515) 294-2567, maharris@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,
jmcguire@iastate.edu
The Red Admiral Takes Flight
By Mary Harris
Curator, Christina Reiman Butterfly Wing
The Red Admiral butterfly, Vanessa atalanta (family Nymphalidae), is a native species that can be recognized easily in your garden as well as in the Christina Reiman Butterfly Wing. The combination of wing coloration and flight behaviors of Red Admirals make them quite conspicuous. Male and female Red Admirals can be recognized by the bright orange-red diagonal band on their forewings. This band continues on the outer margin of the hindwings. The background color of the wings is dark brown-black providing a striking contrast to the red. Finally, when you see the white spots in the apex area of the forewing, you will know you are observing a Red Admiral because no other species has a similar wing pattern.
Behaviorally, Red Admirals are one of the most enjoyable of the native butterflies to watch in Iowa. The males of this species are truly territorial. Territories are maintained so that any female Red Admiral who ventures near will be detected and mated by the keeper of the space. In the late afternoon individual males select a territory in which they regularly patrol. These flight spaces are usually elliptical sunlit areas often oriented along a walkway or clearing among trees. In areas with more hills and mountains than Iowa, this territorial behavior has been noted at the top of rises and is referred to as "hilltopping."
Whether in Iowa or Colorado a territorial Red Admiral male will perch in a sunny spot and dart out at just about anything that moves, including you. If the movement is determined to be another male Red Admiral a chase ensues until the intruder is driven away. Red Admirals are fast and highly maneuverable fliers on wings with an average span of 3.1 centimeters (2 inches) with females usually slightly larger than males.
A second interesting behavior of Red Admirals is their migration. This butterfly species does not overwinter in Iowa. Red Admirals, however, are winter residents in southern Texas and Florida where adults can be seen in flight throughout most of the year. Red Admirals migrate north each spring to repopulate northern North America.
Dr. Royce Bitzer, a postdoctoral research associate in the Entomology Department at Iowa State University, has had a long running fascination with Red Admirals. He has studied both the territorial and migratory behaviors of these butterflies and has developed a Web site (www.public.iastate.edu/~mariposa/homepage.html) where you can learn more about Red Admirals and other closely related species in the genus Vanessa. The site features maps of North America with the dates during spring and summer when Red Admirals first have been seen. Adults typically start appearing in Iowa during the second or third week of April.
According to Bitzer "beginning in early June, the first butterflies of the summer generation will start appearing. These butterflies come from eggs that were laid locally by migrators of the spring generation" which ends by mid June. Bitzer adds that individuals of the summer generation are "readily distinguishable because the adults are considerably larger in size than butterflies of the spring generation. They are also much more stationary than the spring butterflies, and individuals may be recaptured numerous times in an area of a few square kilometers over a period of several weeks."
The host plant eaten by Red Admiral caterpillars is nettle (Urtica spp), but they also have been known to consume hops (Humulus). Adult females can be spotted flying over a patch of nettle alighting occasionally to deposit a single egg on the upper side of a leaf. Neonate larvae are black whereas later stages of larvae may be grey, whitish, green, yellow or brown. All Red Admiral larvae have branched spines, yellow stripes down the sides and white wart-like bumps. The pupa can be found hanging upside down among plants near patches of the host.
The species Vanessa atalanta is native throughout the northern hemisphere including North Africa, North America and Europe. It also has been established on several islands including the Azores, Canary Islands, Hawaii and New Zealand. In addition to the migrations observed in North America, Red Admirals undertake a northward migration each year in Europe. Sometimes they even migrate to the Christina Reiman Butterfly Wing at Iowa State University.
To learn more about the Reiman Gardens at Iowa State University visit us on the Web at: http://www.reimangardens.iastate.edu/.
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Editors: A color photo, suitable for publication, is available at right. Click on the thumbnail photo to go to the fullsized photo. The file size is 560K. Caption: Red Admiral butterfly |
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