Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
1/2/03
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
Owl Butterflies at the Christina Reiman Butterfly Wing
By Linda Naeve
Extension Coordinator
Reiman Gardens
Currently, the entire lifecycle of owl butterflies can be observed at the Christina Reiman Butterfly Wing. Owl butterflies in the genus Caligo are so named because of the large eyespots, or ocelli, on the undersides of the hind wings. When the butterfly lands and folds its wings over its back these eyespots are prominent and threaten would-be predators.
Visitors can look for the large white eggs on undersides of heliconia leaves within the flight house. Species within the plant families Heliconiacae (heliconias) and Musaceae (banana) provide the specific host plants on which owl butterflies deposit eggs and larval growth occur. Although there are no banana plants within the exhibit, there are some heliconias and to save them from these voracious larvae, we remove the eggs and larvae we find.
As the eggs develop they take on a dark appearance and hatch at about day 12. The early larval stages are greenish with dull stripes running the length of their flattened bodies. We place the caterpillars on a leaf in one of the emergence cases where visitors can observe these unusual looking larvae. The larger instars, or larval stages, are brown with a forked tail, spiny head capsule and fleshy projections along the back that can be seen clearly. With these spines and projections the larvae look menacing, resembling the dragons seen in Chinese New Year parades. However, just like the eyespots on the adults, this apparent threat is all a bluff because the larvae are harmless. Feeding occurs at night and by day the larvae line up along the midrib of the leaf and are secretive.
Owl butterflies are in the family Nymphalidae, the "brushfooted butterflies." Nymphalids hold the first pair of legs folded close to the body and use only the second and third pair of legs for walking. Species in the genus Caligo include some of the largest neotropical butterflies occurring from Mexico through South America.
In areas of commercial banana production, owl butterfly larvae are considered economically important pests because of the tremendous amount of foliage they consume. An individual larva can easily eat an entire banana leaf measuring more than 3 feet in length and one foot in width. Owl larvae grow slowly, believed to be the result of low nitrogen levels in their host leaves, and the entire length of feeding may take as long as 45 days. When mature, the larva hangs from a silk pad it spins to attach itself to foliage and then forms the cryptic, delicate chrysalis. The insect then begins the pupal stage during which metamorphosis occurs, changing the owl caterpillar into the owl butterfly. This metamorphosis takes some time and adults emerge from the chrysalis after approximately 3 weeks. Currently, the chrysalides of four species of Caligo can be seen in the emergence cases: C. atreus, C. memnon, C. illiones, and C. eurilochus.
Caligo eurilochus, with a 5-inch wingspan, is the largest owl butterfly in the exhibit. The adults fly at dawn and dusk, resting in between on the plants, rocks and netting in the flight house.
Owl butterflies are one of more than 50 different species currently flying in the Christina Reiman Butterfly Wing at Reiman Gardens. There are more than 800 butterflies in the flight house. It is a beautiful retreat from the cold winter weather.
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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 356K. Caption: Owl butterfly with eggs. |
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