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Nature Watch: Everything from Armadillos to Zebra Butterflies

Insect Planet

Insects are everywhere on planet Earth, from polar region to desert, lake bottom to mountain top, even on and in the bodies of humans. It's hard to pin down how many kinds of insects there are in the world. Somewhere between 750,000 and 1 million species have been described, and some scientists estimate that ten times that number may exist. In contrast, there are only about 400,000 species of all other living things combined, including plants.

There are thought to be at least 200 million times more individual insects than people. That statistic may make your skin crawl, and if it does, be grateful for bats and swallows and other creatures that consume insects by the pound. But also consider the good that insects do: They pollinate flowers; aerate soil; decompose waste; serve as a major food source for fish, birds, and other animals; and provide us with a number of products including honey and silk. Many insects prey on species that humans consider destructive pests. Some of them have even made valuable contributions so science, such as the fruit fly, which has been used in countless genetic experiments. Surely the world would be a very different place without insects.

Insects come in many shapes and sizes. They exhibit an endlessly varied and fascinating range of behaviors. They succeed in a multitude of environments, exploiting almost all possible food supplies. How they manage this, how they live, mate, and die, is as varied as the insects themselves. We've gathered here just a few of their stories and statistics.

Let It Be Beetles: Beetles, order Coleoptera, are not only the largest group of insects, they are the largest order in the animal kingdom. There are so many species that even the best estimates vary, ranging from 300,000 to 500,000 species. It is probable that one out of every four creatures on earth is a beetle.

Multinational Corporation: The world's largest known ant colony stretches 3,700 miles along the southern European coastlines of Portugal, Spain, France, and Italy. Composed of an introduced Argentine species, Linepithema humile, its population numbers in the billions.

A Thousand Years and Counting: The European supercolony beats out the previous record-holder, a colony of wood ants in Japan extending a mere 12 or 15 miles and numbering approximately 307 million ants. The Japan colony is thought to be more than 1,000 years old.

Feather-wing vs. Goliath: The Goliath Beetle, which grows more than 5 inches long and 2 inches wide, is widely considered the world's largest insect species by body mass. Its relative the North American Feather-winged Beetle, measuring a mere 1/100th of an inch in length, is one of the smallest.

World Heavyweight Champion! The heaviest insect ever weighed was not a Goliath Beetle (see above) but a New Zealand creature called a Giant Weta. A female, unusually laden with eggs, weighed 71 grams, or about 2.5 ounces -- about the weight of a chipmunk! Most Giant Wetas never approach that weight.

Calling the NBA: Walkingsticks are the longest insects known. They can have a body length of 12 inches, and the record-holder measured 22 inches with its legs spread out. A big fellow like that has two ways to avoid detection by predators: he blends in with his environment by looking exactly like a twig or stick, and he is able to hold himself perfectly still -- for as long as six hours.

Winged Wonders: Atlas Moths and Birdwing Butterflies have the largest wingspans of all living insects, up to 12-13 inches across.

How Big Is Too Big? The largest insect that ever lived, as far as we know, was a gigantic dragonfly called Meganeura monyi. It had a wingspan of approximately 29 inches.

Tony the Tiger Larva: The Tiger Beetle is a ferocious predator from a very young age. The S-shaped larvae construct vertical burrows in dry soil, anchoring themselves with hooks located on their abdomens. Thus positioned, they seize passing prey with their strong jaws.

Come out or I'm Coming in to Get You! The Boat-backed Ground Beetle may be only 5/8 to 7/8 inch long, but its diminutive size doesn't stop it from preying on snails and slugs. Its narrow head and thorax allow it to reach inside a snail's curving shell, using its long narrow mandibles to seize the animal inside.

Eat Everything Bigger Than Your Head: Mantises are voracious eaters. Large species even stalk small frogs, lizards, and hummingbirds.

Stand Back! It's Going to Blow! Bombardier Beetles are named for their unusual defense mechanism -- they emit from their anal glands puffs of toxic chemical that repel their attackers.

Nozzleheads: Termites, like ants, live in colonies, where various functions are performed by different castes, some of which are sterile and wingless. A few termite species have a "nasute" caste: its members have a nozzle on the head that can be used to spray a repellent fluid at ants and other intruders.

I Yucca You and You Yucca Me: Yucca plants and Yucca Moths need each other. The female moth forms the sticky pollen of a yucca flower into a ball-shaped mass and then carries it to another yucca flower. She inserts a few eggs through the side of the flower's ovary and presses the pollen into the cup-shaped stigma. This ensures that the plant will be cross-pollinated and it will produce a maximum crop of seeds for the future caterpillars to eat.

One-Track Mind: Many mayflies live less than a day as adults, bursting from the water in the evening and dying before dawn. Their sole purpose is to mate. They are not even equipped to feed.

Looking for a Honey: Honeybee queens live for about five years and lay as many as 1,500 eggs/day. Drones (reproductive males) die after mating with the queen. Unmated drones are denied food and die.

Sounds Like EE-EE, ee-ee: There are about 23,000 grasshopper and cricket species worldwide, and each species is said to have its own "song." Insect experts claim that different species can be identified from their distinctive sounds.

Can You Hear Me Now? Some species of cicadas, including two North American natives, are the loudest insects known. They have been recorded at about 106 decibels, louder than an incoming subway train (100 decibels) but just a little quieter than the whine of a power saw (110 decibels).

Let's Rest Here a Minute: The Rocky Mountain Grasshopper (Melanoplus spretus) reached plague proportions in the American West before 1900 but is now probably extinct. The "Grasshopper Glacier" near Cooke, Montana, contains millions of embedded Rocky Mountain Grasshoppers, presumably from swarms that settled on the glacier and froze.

How's My Lipstick? Cochineal Bugs, small red insects found on prickly pear cacti in the desert, yield a red pigment that was used to make a dye by Native Americans of the U.S. Southwest. Today the dye is used to color foods and cosmetics, including lipstick.

20-20 Vision: The more facets (lenses) in an insect's eye the better its sight. Dragonflies have up to 30,000 facets in each eye. They can also swivel their heads, and so have a very wide field of vision.

Hindsight: The neck of a mantis is so flexible that the creature can look over its shoulder -- a feature unique among insects.

Learn more about insects of North America.

Learn more about butterflies and moths.

 

 

 

 

 

2007 eNature.com