Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
1/31/03
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
Giant Swallowtails Have Come to Roost at Reiman Gardens
The giant swallowtail, Papilio (Heraclides) cresphontes, is a member of the family Papilionidae. The genus and species names for this insect are derived from Greek mythology; Cresphonte is one of the Heraclids, or people who claimed to be descendents of Hercules. Swallowtails occur throughout the world, and there are about 500 to 600 species. There are several species of swallowtails native to the United States, and the giant swallowtail is one. As the name implies, this swallowtail is the largest of our native species with a wingspan as great as 6 inches. Giants may be seen throughout Iowa from May to late September, and, at the Christina Reiman Butterfly Wing.
Giant swallowtail adults are easily recognized, not only for their size but also the striking wing pattern that forms an "X." The forewing is black with a wide, diagonal yellow bar meeting large yellow areas on the anterior hindwings. The "tails" of the hindwings each contain an oval yellow spot. When the butterfly folds its wings the pale yellow underwings are visible. The body of this swallowtail is also a pale yellow.
These swallowtails frequent areas of semi open deciduous woodlands east of the Rockies from the Great Lakes region to Central and South America. They fly throughout the day with courtship occurring in the afternoon. Prior to courtship, males can be observed patrolling host plants and flyways, characteristic mate-locating behavior for this species.
The mature caterpillar also may be considered a giant because it can reach a length of 2.5 inches. It is mottled brown with cream-colored patches, including a saddle-shaped patch in the middle. Early instars or larval stages resemble bird droppings and remain motionless during the day and feed at night. Like other swallowtails, giant larvae when disturbed or threatened can evert an osmetarium, a fleshy, forked scent gland. The osmetarium is bright orange-red and is rapidly everted to startle the predator. In addition, the osmetarium secretes an unpleasant odor. This one-two defense drives most predators away, leaving the larva to continue feeding.
Giant swallowtail adults drink nectar and obtain nutrients and moisture from a behavior commonly referred to as "puddling." Giant swallowtail larvae feed on host plants from the Rutaceae family. Members of this family include prickly ash (Zanthoxylum americanum) and hop tree (Ptelea trifoliate) in the northern United States, and torchwood (Amyra) and citrus in the south. In fact, the larva is known as the "orange dog" and considered a pest of citrus in Florida. Plants in this family produce several highly toxic essential oils to deter herbivores. Giant swallowtails are able to use these plants as hosts due to the larva's exceptionally high levels of cytochrome P450 metabolism of the toxins the host plants produce. Humans have similar detoxification systems in the liver and small intestine that allow us to detoxify many potentially harmful substances in our diets.
Many of the butterflies in the exhibit at Reiman Gardens' Christina Reiman Butterfly Wing settle in specific groups to roost for the night. Late in the afternoon, as the light is diminishing, aggregations of zebra longwings, common Mormons and giant swallowtails can be found among the plants in the flight house. At certain times, a group of giants will converge on the foliage above the water feature, providing one of many beautiful sights for visitors.
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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 picture's fullsize photo is 488K. Caption: Roosting giant swallowtail butterflies. |
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