From a population standpoint, insects rule our planet. Scientists have gotten around to naming almost 900,000 different species of insects, but some experts suggest that there may be as many as 30 million more species that haven't yet been christened [source: Smithsonian]. These same scientists estimate that about 10 quintillion--that's 10 with 18 zeroes behind it--insects are alive on Earth at this very minute.
With numbers this staggering, it's no wonder that insects affect our lives and civilization, influencing everything from religion to agriculture to technology. Sometimes the insects' actions are what we perceive as helpful, such as the dung beetle, the sewer worker of the insect world. Sometimes the insects seem to cause harm, like the deer tick, whose bite can inflict Lyme disease. Other times, the purpose of the insect is more ambiguous. It's all part of the world's biodiversity, where the actions of one species often complement another. Each species depends on the other to ensure survival, sometimes in ways we don't yet know.
With that cooperative spirit in mind, keep reading to discover 10 important insects and just what they do to earn that ranking. You'll find out why roaches may not deserve their bad guy label and why the ancient Egyptians put a bug on the chests of their dead.
10. Bees and Other Pollinators
Without bees, flies, midges, butterflies, wasps and beetles, your diet would be a rather grim ration of bread and water. About a third of our food supply comes from plants pollinated by insects, and about 80 percent of that total is pollinated by honeybees [source: MSNBC]. Insects pollinate at least 90 of our fruit and vegetable crops. Some crops require particular insects to pollinate them. For instance, figs could not be grown commercially in North America until tiny wasps were imported from the Mediterranean to pollinate them. Who cares about fruits and vegetables, you say? Don't think you'd just dine on beef without the insect pollinators. Bees pollinate alfalfa, the staple of the beef cow's diet.
9. Silkworms and Other Producers
You know that expensive silk dress your mom always wore on fancy occasions? Nothing but worm spit. Silkworms, which really are caterpillars, not worms, spin a cocoon made of one continuous strand of silk. Workers unwind it and then process the silk thread into cloth. According to Chinese legend, an ancient emperor tested the thread and began making garments as early as 2700 B.C. When the country's longest highway opened nearly 2,600 years later, it was named "Silk Road." The silk industry has been going strong in China for more than 4,000 years, and the silkworms are totally dependent on humans. They are so highly bred by this point that they can't even climb up the plant they live on to get their own food. Another insect that actually produces a product humans use all the time is the lac bug, which secretes a sticky resin onto trees. This resin is scraped off into flakes, mixed with alcohol and made into shellac, a shiny finish for wood. Of course, probably the most famous product produced by an insect is honey, made by the honeybee. Honey is even older than silk, dating back to African and European areas in the Mesolithic area. We like it on this continent too. Americans ate more than 382 million pounds of honey in 2009. No wonder someone came up with the expression, "busy bees" [source: AARP].
8. Dung Beetles
With shimmering green bodies accented with tasteful black highlights, the dung beetle looks much too flashy for his job. But this little insect loves his work so much that in some parts of Texas, he consumes more than 80 percent of all the droppings left by cattle herds [source: ATTRA]. Dung beetles are attracted to manure by its odor, and many dung beetles are species-specific. You wouldn't dare ask a cattle dung beetle to eat the droppings of a horse, for instance. Many dung beetles will hitch a ride on an animal's tail and wait for its next meal. In addition to keeping the pasture tidy, the dung beetle cuts down on the fly population. Flies lay eggs on the dung, and the beetles damage them when they feed.
7. Bad Bugs Doing Good
You certainly won't think of termites and their cousins, cockroaches, as beneficial insects if your house is infested with them, but in the wild, both do valuable work as Mother Nature's housekeepers. Termites recycle tons of cellulose-containing materials, such as dead trees and plants, and return them to the soil as nutrient-rich mulch. Roaches, which are especially partial to moist, warm conditions like those found in rainforests (or kitchens), also break down dead and rotting plant and animal material. In fact, without the primitive cockroach, whose basic design has served it well for about 250 million years, our rainforests would smother in decaying material. Scientists also are proposing that a newcomer to North America, the Asian cockroach, may help cotton farmers by eating pests without harming the cotton plant.
Sure, their bites itch like crazy, and how about that high-pitched buzzing sound when you're trying to go to sleep with one in the room? Those are just petty annoyances compared to this tiny bug's real bite. So for a tiny insect that has a serious bite, look to the female mosquito. The male doesn't bite. Mosquitoes are responsible for some nasty diseases. Yellow fever, brought by the bite of the mosquito, nearly prevented the Panama Canal from being built. Malaria, also carried by mosquitoes, has been the scourge of the tropics for centuries. Some people think that may be a good thing. By keeping people out, the lowly mosquito may have saved what is left of the equatorial rainforest. Up until the last century or so, when people entered the rainforest, mosquitoes bit them -- the people got sick and left, which actually helps the rainforest's ecosystem.
5. Ladybugs and Other Garden Helpers
Don't be so quick with the pesticides when you see a pest on your petunias. Many of the insects you find in your garden are actually your friends, working with you to keep harmful pests at bay. Garden-friendly insects come in two varieties -- predators and parasites. Predators, such as spiders and ladybugs, capture and devour slower and less-intelligent insects, which are often those insects most harmful to your plants. A single ladybug can eat up to 50 aphids a day. Another garden predator, the aptly named assassin bug, eats flies, mosquitoes and beetles, grabbing them with his long spiny front legs. Parasitic insects live off the body of a host insect. Tiny braconid wasps, for example, lay eggs on tomato hornworms, eventually killing them as the larvae mature. The tachinid fly and the trichogramma wasp, both parasitic insects, eliminate a number of vegetable pests, including the cabbage lopper and the squash bug. These garden militia don't sting or bite people or harm plants.
4. Disease Droppers
Throughout mankind's history, it seems that the smallest predators have been the most deadly. The bites of insects transmit all sorts of diseases. Fleas spread black plague in Asia and Europe hundreds of years ago, and mosquito bites spread the more modern epidemic of West Nile virus. In North America, Lyme disease is one of the more common insect-borne illnesses, transmitted to humans through the bite of deer ticks and Lone Star ticks, which can also transmit encephalitis. Trypanosomiasis is one of the stranger diseases transmitted by insects. This disease, known as sleeping sickness, infects more than 70,000 people in Africa each year through the bite of several types of tsetse flies [source: WHO]. Symptoms include itching, swollen lymph nodes, confusion and disorientation, followed by a disrupted sleep cycle. The disease is fatal if left untreated. All over the world, tiny sand flies carry leishmaniasis, a disease of the skin and internal organs. About 1.5 million cases of cutaneous (skin) leishmaniasis are reported each year, as are about half a million cases that affect the internal organs [source: CDC]. Using insect repellent prevents bites from many of the disease-carrying insects.
3. Butterfly Effects
You've probably heard the little anecdote about how the flutter of a butterfly's wing in China can eventually cause a hurricane in New York City. That may be a little extreme, but these most colorful creatures do play their part in the world. In caterpillar form, some moths and butterflies eat pesky insects like mosquitoes, and, as adults, butterflies are eaten in turn by birds, frogs and reptiles. But furthering the food chain is not the butterfly's most important role.
Scientists think the migration of the monarch may have a lot to teach us. The orange and black butterflies go about their business every summer, living out their four- to six-week life spans among the flowers of North America. But as fall approaches, newly born monarchs will live seven or eight months just so they can migrate thousands of miles southward to Mexico, where they have never been. While birds learn migratory routes from their parents, the monarchs' parents couldn't have taught them because they never made the trip themselves. It's as though you were granted a life span of 500 years and told to go back to the place where your ancestors lived, but without any guidance. Scientists believe they can learn a lot about navigation and life span by studying the monarchs, but it's still quite a mystery [source: Journey].
2. Crop Killers
We've already learned about insects that spread disease to humans, so let's take a look at some bugs that infect our crops and livestock. Insects cost farmers more money each year than we can calculate, and the risk of an infestation concerns farmers and the government. For instance, an infestation of Asian longhorn beetles could dry up the maple syrup industry in New England. Mosquitoes and ticks can transmit diseases such as Rift Valley fever and African swine fever to livestock. Insect bites transmit some viruses to plants. When an infected aphid chews on a leaf, it transmits the virus to the cells it damages. While crop viruses are currently impossible to treat, prevention is possible through insect control and the planting of virus resistant species. Insect bites can also pass on bacteria to plants.
1. History's Important Insects
Tiny though they are, insects have had a great impact on humankind. In the late 19th and early 20th centuries, the boll weevil migrated from Central America and Mexico into the United States, practically wiping out cotton as a cash crop for most small farmers, who were forced to diversify or change occupations. Sociologists point to the wave of African-American migration to the industrial cities of the North as a consequence of this infestation.
The scarab beetle -- a form of dung beetle -- lived a far more glamorous life in ancient Egypt. There, the beetle god pushed the sun along the sky in the same fashion as the scarab rolled its ball of dung along the ground. The embalmer of Egypt placed scarab amulets over the hearts of the mummified dead.
The Old Testament mentions locusts (a term usually used for a type of cricket or grasshoppers) as one of the plagues that God sent to Egypt to convince the pharaoh to release the Israelites from slavery. In the mid-1800s the Mormons had just settled in Utah when they were overcome by a huge swarm of what they called locusts (now called Mormon crickets) that were consuming their crops. Miraculously, goes Mormon lore, a flock of seagulls appeared and devoured all the crickets, saving the crops.
For more insect-related information, visit the links on the following page.
Lots More Information
- Insect Pictures
- Importance of Biodiversity Puzzles
- Reptile Pictures
- Endangered Animal Pictures
- Ultimate Insects and Biodiversity Quiz
- Ancient Egypt: The Mythology. "Scarab Beetle." Aug. 1, 2010. (Aug. 22, 2010). http://www.egyptianmyths.net/scarab.htm
- Boston Natural Areas Network. "The Ten Most Important Insects in the Garden." (08/19/2010). http://www.bostonnatural.org/cgGTips_ImportantInsects.htm
- Centers for Disease Control, Division of Parasitic Diseases. "Leishmania Infection." Sept. 22, 2008. (Aug. 24, 2010).
- Centre for Distance Learning and Innovation. "Who Needs Insects Anyway?" (Aug. 19, 2010). http://www.cdli.ca/insect/page3.htm
- Christen, Kris. "Aquatic Bugs on the Frontline." Sightline. Summer, 2001. (Aug. 22, 2010). http://eerc.ra.utk.edu/sightline/WaterV2N1.html
- Easton's Bible Dictionary. "Locusts." (08/22/2010). http://www.christnotes.org/dictionary.php?dict=ebd&id=2309
- Iowa State University, Department of Entomology. "Silk." Oct. 12, 2007. (Aug. 19, 2010). http://www.ent.iastate.edu/dept/courses/ent211/use/silk
- Lange, Olmstead and Rhode. "The Impact of the Boll Weevil, 1892-1932. February, 2008. (Aug. 22, 2010). http://www.econ.ucdavis.edu/faculty/alolmstead/Working_Papers/BOLL%20WEEVIL%20.pdf
- Klaus, Michael W. "Mormon Cricket." Washington State University Tree Fruit Research and Extension Center. January, 2008. (08/22/2010). http://jenny.tfrec.wsu.edu/opm/displaySpecies.php?pn=253
- Krulwich, Robert. "Three Nice Things We Can Say About Mosquitos." National Public Radio. July 30, 2008. (08/19/2010). http://www.npr.org/templates/story/story.php?storyId=93049810
- MSNBC. "Declining honeybees a ‘threat’ to food supply." May 2, 2007. (Aug. 23, 2010). http://www.msnbc.msn.com/id/18442426/
- National Academy of Sciences. "About Pollinators." (08/23/2010). http://dels-old.nas.edu/pollinators/aboutpollinators.shtml
- National Sustainable Agriculture Information Service. "Dung Beetle Benefits in the Pasture Ecosystem." 2001. (08/23/2010). http://attra.ncat.org/attra-pub/dungbeetle.html
- National Public Radio. "Bedbugs Aren't Just Back, They're Spreading." Aug. 21, 2010. (Aug. 22, 2010). http://www.npr.org/templates/story/story.php?storyId=129345182&ps=cprs
- Oberhauser, Karen. "Monarch Butterfly Journey North." (Aug. 19, 2010). http://www.learner.org/jnorth/search/MonarchNotes3.html#6
- Smithsonian Institution. "Bug Info: Numbers of Insects (Species and Individuals)." (Aug. 22, 2010.) http://www.si.edu/encyclopedia_si/nmnh/buginfo/bugnos.htm
- Tampa Bay Regional Planning Council. "Agricultural Diseases and Pests." (Aug. 19, 2010). http://www.fldisasterkit.com/hazards_analysis/agricultural_pests.shtml
- U.S. Global Change Research Information Office. "Impacts of Introduced Species in the United States." Nov. 11, 2004. (08/19/2010). http://www.gcrio.org/CONSEQUENCES/vol2no2/article2.html
- Woodell, Debra. "Honey is Sweet, Healthy, Nearly Immortal -- and Endangered." Aug. 12, 2010. (Aug. 27, 2010) http://www.aarp.org/food/diet-nutrition/news-08-2010/honey_is_sweet_healthy_nearly_immortal_and_endangered.html
- Woodland Park Zoo. "Animal Fact Sheets: Madagascar Hissing Cockroach." (Aug. 24, 2010). http://www.zoo.org/Page.aspx?pid=475
- World Health Organization. "African trypanosomiasis (sleeping sickness)." August, 2006. (Aug. 24, 2010). http://www.who.int/mediacentre/factsheets/fs259/en/