Cracker butterflies are a Neotropical group of medium-sized brush-footed butterflyspecies of the genusHamadryas. They acquired their common name due to the unusual way that males produce a "cracking" sound as part of their territorial displays. The most comprehensive work about their ecology and behavior is that of Julian Monge Najera et al. (1998).[1][2] The genus was erected by Jacob Hübner in 1806.
Cracker butterflies are all fairly cryptic in their dorsal coloration, commonly covered in varying colored spots, most of which resemble bark; some are known to have little coloration, such as the Hamadryas februa.[3]
Distribution and habitat
This genus of butterflies are commonly found throughout South America to Arizona, where at least nine species can be found in Costa Rica.[4][5][6]
They spend most of the day perching on trees, boulders, and other such surfaces against which they are camouflaged. The speckled species of Hamadryas are often hard to distinguish, and most often these butterflies have to be examined as set specimens. There are no recent revisions, but a general account was published by D.W. Jenkins.[7]
Since cracker butterflies have good camouflage, they are not poisonous and do not have a chemical defense, with the exception of the starry night cracker. They are fed upon by rufous-tailed jacamars.[4]
Behavior
Male cracker butterflies are known for their ability to make a cracking noise with their wings, which is believed to either be for mating or to ward off rival males. They use trees as courting territories, as shown by experiments. They prefer to perch on trees with bark that matches their wing coloration, while the presence of food, position of trees along flight routes, tree size, bark texture, and lichen cover are not associated with the frequency of perching on the trees.[1][8]
Each species has a height range when perching but they perch higher when night approaches. The northern side of trees is less used and cardinal-direction side distribution is independent of time of day. Perches exposed to direct sunlight are less used in hot days. All species perch with the head downwards[citation needed]. Perching males frequently fly towards other butterflies.[1]
Each male perches on one to four trees daily, without difference between seasons, and each tree used has a minimum daily mean of 1.5 perching butterflies. Most interactions occur from 13:00 through 15:00 hours and are more frequent in the rainy season. At night males share perches.[1]
At least seven locations have been proposed for the sonic mechanism of Hamadryas butterflies. Non-destructive experimental methods and scanning electron microscopy suggest that both sexes emit sound and the sound apparatus, located in the forewing, is percussive, not stridulatory. At the end of the upward wing stroke, the wings are clapped and modified r-veins meet at a speed of approximately 1420mm/s, producing the characteristic clicks. Wing beat frequency of free-flying individuals is 20–29Hz. Clicks last a mean of 1.38ms with mean intervals of 43.74ms and the component frequencies concentrate around 2.4kHz, matching Hamadryas hearing capacity and being appropriate for the acoustic conditions of habitat.[1]
The swollen Sc vein is present exclusively in Hamadryas; has a serpentine structure inside and probably acts as resonance box. Growth of the sound apparatus may be checked by its effect on flight capacity, physiological costs, and ecological reasons.
All Hamadryas have a membrane, shaped as an elongated cupola, in the costal cell, that acts as an ear. A second and smaller ear has four chambers and may detect predatory bats when the insects are perching at night.[1]
In the field, Hamadryas emit audible clicks when approached by potential predators, to defend territories from other Hamadryas and in at least one species also during courtship. Severe wing damage, common in wild Hamadryas, almost never affects the section with the sound mechanism. More than 50 species of lepidopterans (11 families) emit sound which can be audible to humans 30 meters (100ft) away.[9] In general, lepidopteran sound is used as a warning to predators and for intraspecific communication.[1]
Research has shown that cracker butterflies can also detect the sounds made by other butterflies, which would be a form of social communication.[10] The organ of hearing is believed by some to be Vogel's organ, located at the base of the forewing subcostal and cubital veins.[8][10]
However, they may actually have a larger hearing organ for lower sound wave frequencies.[1]
Food sources
Unlike most butterflies, these species don't feed on nectar. Instead, cracker butterflies feed on rotting fruit, sap from leguminous trees, and animal dung.
Life cycle
Cracker butterflies undergo metamorphosis just like any other species of Lepidoptera, but lay their eggs only on the host plants that are members of the euphorbia family, Dalechampia spp.[4]
Species
The following species are usually included in this genus:[5][6][11]
The morpho butterflies comprise many species of Neotropical butterfly under the genus Morpho. This genus includes more than 29 accepted species and 147 accepted subspecies, found mostly in South America, Mexico, and Central America. Morpho wingspans range from 7.5 cm (3.0 in) for M. rhodopteron to 20 cm (7.9 in) for M. hecuba, the imposing sunset morpho. The name morpho, meaning "changed" or "modified", is also an epithet.
Archaeoprepona demophon, the one-spotted prepona, banded king shoemaker, or demophon shoemaker is a butterfly belonging to the family Nymphalidae.
Biblidinae is a subfamily of nymphalid butterflies that includes the tropical brushfoots. This subfamily was sometimes merged within the Limenitidinae, but they are now recognized as quite distinct lineages. In older literature, this subfamily is sometimes called Eurytelinae.
Agrias is a genus of Neotropical charaxine nymphalid butterflies found in South and Central America.
Ithomiini is a butterfly tribe in the nymphalid subfamily Danainae. It is sometimes referred to as the tribe of clearwing butterflies or glasswing butterflies. Some authors consider the group to be a subfamily (Ithomiinae). These butterflies are exclusively Neotropical, found in humid forests from sea level to 3000 m, from Mexico to Argentina. There are around 370 species in some 40–45 genera.
Nessaea is a genus of nymphalid butterflies found in the Neotropical realm. Unlike virtually all other butterflies with blue coloration, the blue colors in this genus are due to pigmentation [pterobilin ] rather than iridescence.
Eunica is a genus of nymphalid butterflies found in the Neotropical realm.
Tellervini is a tribe of danaid butterflies with only the one genus Tellervo, with six widely distributed species found in the Australasian realm and the Indomalayan realm. The taxon is apparently monophyletic, but its relationship with the other two danaid tribes is yet uncertain. The phylogeography of the group is also a challenge to those who hold to a Cenozoic origin of the butterflies.
Hamadryas laodamia, the starry night cracker or starry cracker, is a species of cracker butterfly in the family Nymphalidae. It can be found from Mexico to the Amazon basin, but is most common in lowland forest in the Caribbean area.
Hamadryas feronia, the blue cracker or variable cracker, is a species of cracker butterfly in the family Nymphalidae. It is found in the southern parts of North America and southwards to Brazil.
Julián Monge-Nájera (born June 6, 1960, in San José is a Costa Rican ecologist, scientific editor, educator and photographer. He has done research with the following institutions: Universidad de Costa Rica, Smithsonian Tropical Research Institute, and Universidad Estatal a Distancia. His scientific work has been featured by The New York Times; National Geographic Magazine; the BBC; Wired; IFLoveScience; The Independent and The Reader's Digest, among others. He is a member of the Expert Panel that sets the Environmental Doomsday Clock; Onychophora Curator in the Encyclopedia of Life; and Team Member of the IUCN Red List of Threatened Species.
Nessaea obrinus, the obrina olivewing, is a species of butterfly of the family Nymphalidae. It is found from Colombia and the Guianas to the mouth of the Amazon and south to central Bolivia and Mato Grosso in Brazil, extending to northern Argentina.
Hamadryas epinome, the epinome cracker, is a species of butterfly believed to have originated from Paraguay and also found in a number of other South American countries including Argentina, Brazil, Peru, and Uruguay.
Hamadryas februa, the graycracker, is a species of cracker butterfly in the family Nymphalidae. It is found from Argentina north through tropical America to Mexico. Rare strays can be found up to the lower Rio Grande Valley in southern Texas. The habitat consists of subtropical forests, forest edges and cultivated areas with trees.
Hamadryas albicornis is a species of cracker butterfly in the family Nymphalidae. It is found in Peru.
Marpesia zerynthia, the waiter daggerwing, is a species of butterfly in the family Nymphalidae that occurs in, and somewhat north and south of Mesoamerica.
Hamadryas iphthime, the ringless blue cracker or brownish cracker, is a species of cracker butterfly in the family Nymphalidae. It was first described by Henry Walter Bates in 1864. It is found in Mexico, Central America and parts of northern South America.
Dalechampia triphylla is a vine in the family Euphorbiaceae. It is native to tropical South America.
Hamadryas glauconome, the pale cracker or glaucous cracker, is a species of cracker butterfly in the family Nymphalidae. It was described by Henry Walter Bates in 1864 and is found in Mexico, Central America and south to Peru. It has been recorded as an unexpected vagrant in the United States in southern Florida, Arizona and Texas.
Napeocles jucunda, the great blue hookwing, is a South American butterfly of the family Nymphalidae. The species was first described by Jacob Hübner in 1808.
References
1 2 3 4 5 6 7 8 Monge-Nájera, J., F. Hernández, M.I. González, J. Soley, J.A. Pochet & S. Zolla. (1998). Spatial distribution, territoriality and sound production by tropical cryptic butterflies (Hamadryas, Lepidoptera: Nymphalidae): implications for the "industrial melanism" debate. Revista de Biología Tropical. 46 (2): 297-330.
↑ Jenkins, D.W. (1983): Neotropical Nymphalidae. I. Revision of Hamadryas. Bulletin of the Allyn Museum81: 1-146.
↑ McAndrew, Brian (January 2000). Niagara Parks Butterflies. Wilson, Simon (photographer). Lorimer, James & Company, Limited. pp.40–41. ISBN1-55028-700-1.
1 2 3 Henderson, Carrol L.; F. Skutch, Alexander (May 2002). Field Guide to the Wildlife of Costa Rica. Corrie Herring Hooks Series. Henderson, Carrol L. (Photographer) (1STed.). University of Texas Press. pp.42 & 43. ISBN0-292-73459-X. Retrieved 2009-09-24.
1 2 Garwood, K.M.; Lehman, Carter W. & Carter, G. (2007). Butterflies of Southern Amazonia. Neotropical Butterflies, Mission, Texas.
1 2 Lamas, G. (ed.) (2004): Atlas of Neotropical Lepidoptera (Checklist Part 4A. Hesperioidea-Papilionoidea). Association for Tropical Lepidoptera, Gainesville, Florida. ISBN0-945417-28-4
1 2 Yack, Jayne E.; Otero, L. Danier; Dawson, Jeff W.; Surlykke, Annemarie & Fullard, James H. (2000): Sound production and hearing in the blue cracker butterfly Hamadryas feronia (Lepidoptera, Nymphalidae) from Venezuela. Journal of Experimental Biology. 203 (24): 3689–3702. PDF full text
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