The Largest Insects on Planet Earth

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.