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Mary Harris, Reiman Gardens, (515) 294-2567,
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,

The Archduke Reigns

By Mary Harris
Christina Reiman Butterfly Wing

The Archduke, Lexias dirtea, may cause visitors at Reiman Gardens to do a double take when they visit the Christina Reiman Butterfly Wing. This old world tropical butterfly is one of a group of related species in which the males and females are strikingly different but equally beautiful. Males are velvety dark brown, almost black, with the trailing edge of the forewing a shimmering blue. The majority of the hind-wing is a combination of violet, blue and green.

The female, or perhaps we should refer to her as the Archduchess, is also a velvety brown, but there the resemblance to the male ends. The female lacks shimmering blues or greens and instead displays several rows of orange-yellow spots that run from one side of a wing across the body and across the other wing. The continuation of the wing pattern across the thorax and abdomen is unusual and fun to look for as one observes the many butterflies in the exhibit at Reiman Gardens.

Lexias dirtea originates from Asia with different races inhabiting forested areas of Manipur, Burma, Malaysia and the Philippines. The species was first named and described by Fabricius in 1793 as Papilio dirtea. J. G. Koenig, most likely took the specimen that Fabricius examined in 1779 during a collecting expedition to Malaysia. Although Koenig was not a lepidopterist, he collected many of the type specimens from which the butterflies of Southeast Asia have been described. The species originally described as P. dirtea was subsequently placed within the genus Euthalia and finally moved to Lexias. Lexias dirtea is a brush-footed butterfly, in the family Nymphalidae, and is the largest species in this genus in Malaysia with a wingspan of 85 to 100 millimeters.

Members of the genus Lexias have extremely ornate caterpillars, which are protected by long feathery spines that render the larva inaccessible to predators. When at rest, the caterpillar aligns itself along the midrib of a leaf.

The L. dirtea chrysalis, or pupal stage of the butterfly, is 24 to 30 millimeters long, somewhat triangular shaped at one end and sharply pointed at the other end. The chrysalis is pale green with a pronounced "shoulder," the edge of which is light brown. The Archduke chrysalides and newly emerged adults may be viewed in the emergence cases in the lobby at Reiman Gardens.

Adult Archdukes are inhabitants of primary forests, and both males and females are attracted to sunlit areas such as paths or clearings, recent tree-falls, and forest edges. The females are more cryptic than the males that have evolved their bright coloration to be noticeable to other males as they compete for females. However, competition is not too great, as it has often been observed that there is a greater number of females in flight than males.

In addition to the unusual degree of sexual dimorphism, the Archduke (and duchess) is unusual in the range of its feeding behaviors. As adults, members of this species primarily feed on rotting fruit, particularly pineapples and mangosteens, fruits of trees in the genus Garcinia. At the Butterfly Wing, we provide dishes of fruit to satisfy the needs of the exhibit species of butterflies that require this delicacy in their diets. The Archduke is alone among the species that feed on fruit, however, in that it also will visit flowers to take in nectar. All in all, this combination of feeding behaviors, along with the strong sexual dimorphism, make the Archduke a very interesting exhibit species to see at the Christina Reiman Butterfly Wing.

To learn more about the Reiman Gardens at Iowa State University visit us on the Web at:


Editors: Two color photos, suitable for publication, are available at right. Click on each photo to download. The top picture's fullsize photo is 20K and the bottom picture's fullsize photo is 20K.

*NOTE: There are no high-resolution photos this week; both photos are 72 dpi.

Caption: Female Archduke (Lexias dirtea).

Caption: Male Archduke (Lexias dirtea).

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