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Thursday, May 8, 2008

The Largest Insects on Planet Earth

Cannibals, dancers, and pheromone emitters—some of the largest (and endangered) insects in the world are nurturing mothers in the wild, wearing poison as perfume, and crawling up human backs as friendly pets.

Giant Walking Stick


Photo courtesy of tajai (cc)

Considered one of the best tropical insects to keep as a pet, the stick insect (Phasmatodea) derives from the Greek word, “phasma” (meaning phantom), which refers to its ability to disguise itself as varied species of sticks and leaves. The longest in the insect kingdom, it can measure up to almost two feet long. Many species of female stick insects live alone, reproducing asexually. Stick bugs are vegetarian but also molt numerous times to eat their own shed skin. When they perceive a threat, they fall to the ground and play dead or dance for hours, swaying back and forth.

Goliath Beetle


Photo courtesy of Conservation International

Native to the African rainforest, the Goliath Beetle is one of the largest insects on earth according to its size, weight, and mass. They measure up to five inches in length and can reach up to four ounces while in their larval stage, before reducing their weight to half as adults. Equipped with an armored shell, adult Goliaths produce a toy helicopter sound once their two pairs of wings emerge and they take flight. Male Goliath beetles have a Y-shaped horn on their heads to battle other males for feeding sites or females, while females have a wedge-shaped head to assist them in burrowing when they lay eggs. Though they feed on ripe fruit and tree sap in the wild, they enjoy cat and dog food when raised in captivity.

Atlas Moth




Photos courtesy of Sean Dockery (cc) and Lionoche (cc)

Found only in Southeast Asia, the Atlas Moth is the largest of the moth species with the largest wing surface area—close to sixty-five square inches—and a wingspan of up to a foot long. Named after wing patterns that resemble maps, the moth’s wing tips resemble a snake’s head in order to ward off predators. With no mouth, it feeds off fat reserves built up during their caterpillar stage. Females secrete a pheromone through a gland at the end of the abdomen that males can detect several miles downwind. Adults mate quickly, since a total lifespan of a female is only one to two weeks. Females lay their eggs, use up their fat reserves to feed themselves, and then quickly die.

Queen Alexandra’s Birdwing




Photo courtesy of khasan

Named after Queen Alexandra of England (1844-1925), the Queen Alexandra Birdwing (Ornithoptera alexandrae) is the largest butterfly in the world. Found in Oro Province in eastern Papua New Guinea, females are predominately larger than males and have a wingspan of up to fourteen inches. Birdwings feed on the aristolochia plant (Aristolochia schlecteri) to lay their eggs, which contains a poisonous substance that when digested by the caterpillar makes it distasteful to predators. Endangered since 1989, the Birdwing has experienced habitat loss caused by agriculture, logging, and human advancement.

Giant Weta




Photos courtesy of Dr Paddy Ryan-Ryan Photographic

The Giant Weta, New Zealand’s largest insect, can be four inches long and weigh almost three ounces, while a pregnant Weta can weigh more than a small sparrow. Nocturnal and flightless, the Weta raises its hind legs when frightened, flicking its legs down in hope of “spiking” a predator’s face. Other times Wetas lie on their backs to play dead, exhibiting their vulnerability. One tagged and researched male Weta walked over nine miles in one night in search of a female (females tend to stick closer to home, moving at an average of thirty-three meters at night). Since becoming extinct from New Zealand’s mainland one hundred years ago, the Giant Wetas now live on offshore islands. Its decline stems from predatory mammals, and habitat destruction/modification.

Chinese Mantis




Photo courtesy of GRBerry (cc) and Mark Williamson (cc)

Introduced to North America in the late 1800s as a form of pest control, the Chinese believed the mantis may cure conditions ranging from impotence to goiters. They also believed roasting the mantis’ egg cases and feeding them to children could stop bed-wetting. Chinese mantis can grow up to four inches in length and are the largest mantis species on the continent. Though they mainly eat insects, most are cannibals. Females can capture and digest small reptiles and amphibians, as well as hummingbirds. When hunting, they assume a “praying” position and fold their legs under their head, until they unfold to strike and capture their prey. When mating, a smaller male usually jumps on the back of a large female, and eventually may become her meal. During copulation, the female may turn and consume the male’s head, keeping his body to complete mating until finished, when she can eat the rest of his body.

Giant Dragonfly


Photo courtesy of Wikipedia

Recently placed on the Endangered Species list in Australia from degradation of wetland habitats, the Giant Dragonfly (Petalura gigantean) is considered a terrestrial species throughout most of its life. As true carnivores, dragonflies fly over and grab the insects they consume. Females tend to be larger, reaching a wingspan of almost six inches. Males patrol swamps while females fly in from a surrounding area to mate. If the female does not accept the male, she will curve her abdomen downward, but if accepted, the male grasps and clasps her, commencing their tandem mating flight. Just before copulation, sperm moves from the male’s first genitalia into his secondary genitalia, then the female will lay her eggs one-by-one deep into the swamp’s peat moss.

Giant Burrowing Cockroach


Photo courtesy of Natural History Museum-London

Native to North Queensland, Australia, the Giant Burrowing cockroach is the world’s heaviest cockroach species. They can weigh over one ounce and grow to over three-inches long. Since they don’t have wings, they are not considered a pest and can live up to ten years in the bush. Some believe the species to be great pets due to their cleanliness, odorlessness, and inability to crawl out of a tank. The name “burrowing” comes from the burrows they dig, three feet deep, making them the only cockroach species to construct underground burrows to live in. Eating dead eucalyptus leaves to prepare for yearly reproduction, females birth one litter of five and thirty young nymphs that stay with their mother for up to nine months before constructing burrows of their own.

Giant Water Bug


Photo courtesy of NoiseCollusion (cc)

Not a loofah for a human’s back, but eggs carried on the back of the male Giant Water Bug. The largest bug in the cicada family, the Giant Water Bug can grow to five inches and will painfully bite that which dips beneath the water’s surface. Considered one of the worst bites in the insect kingdom—and a delicacy for humans in Thailand—the Giant Water Bug feeds on fish, amphibians, and crustaceans. Their saliva stuns their prey while they suck out the prey’s liquefied remains. When the prey resembles a human, the water bug plays dead, emitting fluid from its anus. Females deposit their eggs onto the males, who raise the eggs by exposing them to air (to avoid the growth of fungus) until the eggs hatch into the nymphs three weeks later, proving that a mother’s work (even when not carrying the child) is still never done.

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