The Amazon rainforest, a realm of unparalleled biodiversity, teems with captivating creatures, among which the blue morpho butterfly stands out as a beloved and emblematic species. With their striking blue color and shiny wings that reflect light, these butterflies are easily spotted amidst the jungle canopy. Blue morphos are one of the largest butterflies in the world, measuring around six inches long and with wing spans of up to 20 centimeters. Found throughout the forests of South and Central America, especially Brazil, Costa Rica, and Venezuela, their habitat extends into North America as well.
What is a Blue Morpho?
The name “blue morpho” can be used to refer to any blue butterfly of the genus “morpho,” which is part of the larger Nymphalidae family. There are 29 morpho species, including the brown, green, and rare white butterflies. The name “morpho” is thought to originate from the butterflies' apparent change in shape as they fly. To compensate for their vivid blue color, which could attract predators, the underside of the butterfly’s wings are covered in shades of brown, red, black, and grey, resembling foliage for camouflage. Their undersides also feature “ocellie” or eyespots, which deter predators when the butterflies are at rest and their wings are closed. When threatened, the butterfly emits a strong odor from a gland on their front legs, which repels predators. The blue morpho also has a “flashing” defense; in flight, its wings appear to flash from vivid blue to dull brown.
These butterflies are covered in shimmering shades of blue on their upper wing surfaces, a coloration typically exhibited by males to intimidate rival males (blue morpho butterflies are highly territorial) and attract potential mates. Females generally have wings exhibiting various shades of brown, yellow, and black. The Blue Morpho’s wings are not actually blue at all! This appearance is caused by the way light reflects off the microscopic scales on its wings. The scales are diamond-shaped, and the color results from their specific formation and placement on the wing membranes. These diurnal butterflies are most active when the sun is shining. Their eyes are highly sensitive to UV light, and the males are particularly adept at spotting each other across great distances. In light-filled environments, they are especially visible, as the sun rays reflect off their shiny wings. Blue Morpho butterflies have even been spotted flying through the jungle canopy by pilots from the air.
From Leaf-Chomping Caterpillars to Juice-Sipping Adults
The blue morpho's diet changes dramatically throughout its life cycle. As caterpillars, they start their lives feeding on various plants, particularly those of the pea family. Blue morpho caterpillars are especially fond of leaves in the pea family. But after transforming, they quickly graduate to a more varied and interesting diet, despite the fact they can no longer chew. They drink the juices of rotting or fermenting fruit using their proboscis, a long mouthpart that acts like a straw enabling them to suck up the sweet fluids. They’ve also been known to drink the juices of tree sap, fungi, decomposing animals, and even wet mud. Unlike most butterflies, they do not visit flowers for nectar.
Larval Diet: A Vegetarian Start
Upon hatching from their small, light green eggs, the larvae, or caterpillars, of the blue morpho butterfly begin their voracious feeding on host plant leaves. The caterpillars of Blue Morpho butterflies are notable for their reddish-brown color and white patches. The hairy brown caterpillars feed on a variety of leguminous plants (a simple dry fruit which develops from a simple carpel and usually opens along a seam on two sides). Several host plants of Morpho peleides larvae have been identified, and the species is thought to have a very broad host range. According to Urich and Emmel (1991), the primary wild host plant in Trinidad is Paragonia pyramidata (Bignoniaceae), and females were observed laying eggs on Erythrina glauca and Erythrina micropteryx (both Fabaceae). Machaerium salvadorensis (Fabaceae) is the major host plant of some Morpho peleides in El Salvador, and several legumes (Fabaceae) have been reported as hosts for Morpho peleides in Costa Rica. In some species the caterpillars are cannibalistic. If disturbed, some Morpho caterpillars will secrete a fluid smelling of rancid butter. The tufts of hair decorating the caterpillars have been recorded to irritate human skin.
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Adult Diet: A Taste for the Decaying
As adults, Blue Morpho butterflies feed primarily on the juices from rotting fruits. The adult Morpho peleides butterflies are frugivores, or fruit feeders, and often feed on decaying fruits. They use their proboscis, a long, tube-like mouthpart, to suck up the fermenting juices. Morpho butterflies drink their food rather than eat it. It uses its proboscis (long, protruding mouth part) to drink sap and fruit juices. They have been observed feeding on tree sap from Samanea trees (Fabaceae) (Young 1975). The adults typically feed on tree sap when decaying fruit is unavailable.
Adults use a long, protruding mouthpart called a proboscis as a drinking straw to sip the juice of rotting fruit, the fluids of decomposing animals, tree sap, fungi and wet mud. Morpho butterflies taste with sensors on their legs and taste-smell the air with their antennae. Morpho butterflies feed on the juices of fermenting fruit with which they may also be lured. The inebriated butterflies wobble in flight and are easy to catch. Morphos will also feed on the bodily fluids of dead animals and on fungi. Therefore, Morpho butterflies may be important in dispersing fungal spores.
More About the Blue Morpho
Blue Morphos have long been a source of great fascination to humans. Traditionally, the indigenous peoples of the Amazon associated the butterfly with a long list of superstitious beliefs, considering them both wish granters and evil spirits. More recently, their light-reflecting abilities have been of great interest to scientists.
Unfortunately, Blue Morphos face many potential predators and threats in their rainforest home. Whilst not directly endangered, like many Amazon species they are threatened by deforestation and habitat fragmentation. Their beauty also makes them a target for those wanting to capture them for artistic or collection purposes, and even to make jewelry out of their wings.
Life Cycle
Like all butterflies, Morpho butterflies pass through four distinct phases of metamorphosis. First, the pale green eggs that resemble dewdrops hatch into larvae, better known as caterpillars. After a while, the caterpillars wrap themselves in a protective enclosure, called a chrysalis. At this stage the insects are called pupae. After some time, pupation ends and the mature butterfly emerges from its chrysalis. The entire life cycle of the Morpho butterfly, from egg to death, is approximately 115-137 days. The adults live for about a month. They have few predators as the adults are poisonous due to the feeding caterpillar sequestering poisonous compounds (the process of animals accumulating poisonous compounds from the food they are eating in order to become poisonous themselves for their predators).
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The eggs of Morpho peleides are small (approximately 1-2 mm in diameter), smooth, hemispherical, and laid on the upper surface of leaves. They are light green in color and have a circular band of small brown spots near the top. The larval stage of Morpho peleides has five instars or molts. All stages of larvae are known to feed at dawn and dusk. When they are not feeding, the larvae remain motionless. A study by Urich and Emmel (1991) found that the larvae grow from 5.25 mm in length after hatching up to 93 mm in length at the fifth instar, and another study by Constantino and Corredor (2004) described the larvae as reaching 74.1 mm at the fifth instar. The pupal stage of Morpho peleides lasts approximately 14 days. During this time, the pupae are a pale green color and oval in shape. The adult Morpho peleides butterflies have black bodies and bright, iridescent blue wings, with the underside of the wings being cryptic brown. The margins of the wings have a black border, which is larger in females than in males. This black border has five or six white spots in the center, beginning at the apex of the forewing and extending downward.
Habitat and Behavior
Morpho butterflies are neotropical butterflies found mostly in Central America as well as Mexico and South America including Brazil, Costa Rica and Venezuela. Morpho Butterflies dwell in the forest canopy layer and rarely come near the understorey and forest floor layers.However, they have sometimes been observed flying near the ground in clearings.
Males are territorial and will chase any would-be rivals. Morpho butterflies are diurnally active (active during the day) and have the capability of ‘crypis’, meaning when they sleep at night, they fold their wings so that only the dark underside is seen, making them less visible to predators. It also has a ‘flashing’ defence mechanism, meaning, due to the slow beating pace of their wings, the iridescent blue is flashed and then disappears as the wings are raised only to return in another place in a short while. This causes predators to loose track of the Morpho butterfly when it is flying as they only glimpse blue flashes as the brown underside makes them invisible in the thick foliage of the jungle.
Anatomy and Appearance
As its common name implies, the blue morpho butterfly’s wings are bright blue, edged with black. The blue morpho is among the largest butterflies in the world, with wings spanning from five to eight inches. Their vivid, iridescent blue coloring is a result of the microscopic scales on the backs of their wings, which reflect light. The underside of the morpho’s wings, on the other hand, is a dull brown color with many eyespots, providing camouflage against predators such as birds and insects when its wings are closed. When the blue morpho flies, the contrasting bright blue and dull brown colors flash, making it look like the morpho is appearing and disappearing. The males’ wings are broader than those of the females and appear to be brighter in color.
The males bright coloring is designed to intimidate any rivals that might fly into his territory. The males wings reflect the bright, iridescent color over an extremely wide angle, to maximize its visibility in the rainforest. These colors are not a result of pigmentation but rather are an example of iridescence (an optical phenomenon characterized as the property of surfaces in which hue changes according to the angle from which the surface is viewed). The colors produced vary with viewing angle, however they are actually surprisingly uniform, perhaps due to the tetrahedral (diamond-like) structural arrangement of the scales. This structure may be called a ‘photonic crystal’. The ventral side is decorated with ‘ocelli’ or eyespots. Not all Morpho butterflies have iridescent coloration, however, they all have ocelli. The eyes of Morpho butterflies are thought to be highly sensitive to UV light and therefore the males are able to see each other from great distances.
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