Owl Butterfly (Caligo memnon)
Spanish name: Buho
This butterfly frequently rests near banana crops or other agricultural areas. It is common in lowland forests, but cannot survive in areas with lots of rainfall.
Speaking generally, the caligo can be found from southern Mexico down through Central America and Colombia and into Peru and the Amazon. Within Costa Rica, this species exists on both coasts, but is more common on the Pacific slope. This species can live through the long dry seasons in the Guanacaste region of the country. It can live as high as 1,500 m in elevation.
Curú National Wildlife Refuge, Barra Honda National Park, Palo Verde National Park, Cahuita National Park, Monteverde Cloud Forest Reserve, Guanacaste National Park, Santa Rosa National Park, Children’s Eternal Rainforest Reserve, and Rincón de la Vieja National Park.
Two helpful characteristics to identify this butterfly are its large size and eye spots. One of the largest butterflies in Central America, the caligo often sits with its wings closed, showing only the brown and gray undersides decorated with large, yellow-ringed eye spots. This isn’t the only owl butterfly species in Costa Rica, but Caligo memnon has a particular region of yellowish cream scales on the upper wings. This blends into dark bluish colors on the outer edges.
The caterpillar stage of this species is also distinct because of its enormous size. It is a soft striated brown with black spines projecting out of its back. These look painful, but deceptively so. The reddish head has thick “horns,” and the tail is wide and forked. The chrysalis can be pale green to dull brown, and from below resembles the head of a viper.
Biology and Natural History
The caterpillars start small, but become gigantic, and can be conspicuous on the leaves of banana plants or other host plants. This owl butterfly is more visible around dawn and dusk, but may also be active during the day. It remains in shadier patches of forest and hides well, but is hard to miss when it takes flight. When flying the owl butterfly rises and falls as the large wings alternately show dark brown and purplish blue.
The brown pattern on the underside of its wings does help it blend in with the surrounding forest, but the large, brown, eye-shaped circles on each wing may also resemble the eye of a larger animal. The purpose may be to draw a predator to aim for “eye” on the lower edge of the wing (which it mistakes for a head), which may give the butterfly a greater chance of escaping with its life and only lose part of a wing. When the caligo is startled from its resting place on a tree trunk, it flashes open its wings as it tries to escape, exposing the dusky blues and purples that were hidden when closed.
Butterflies in this family are drawn to feed on the juices of fermenting fruits. Banana, pineapple, and mango are very attractive to this butterfly as an adult. When it is a caterpillar, banana and heliconia are the main host plants.
One of the largest caterpillars in Costa Rica, Caligo memnon bodies can reach 15 cm in length. As adults, the butterfly wingspan is usually 12 to 15 cm.
DeVries, Philip J. The Butterflies of Costa Rica and Their Natural History: Papilionidae, Pieridae and Nymphalidae. Princeton, NJ: Princeton University Press, 1987.
DeVries, P. J. in Janzen, Daniel H. Costa Rican Natural History. Chicago: University of Chicago Press, 1983.
Goode, Mark R. An Introduction to Costa Rican Butterflies. San José, Costa Rica. 1999. ISBN 9977-12-365-9.
Kricher, John. A Neotropical Companion: an introduction to the animals, plants, and ecosystems
of the New World tropics. Princeton University Press: Princeton, NJ, 1997.
Hogue, Charles L. Latin American Insects and Entomology. University of California Press: Berkely and Los Angeles, 1993.
-Amy Strieter, Wildlife Writer