What Good Are Bugs?
by Gerry Bishop; art by David Sheldon
Photos by Jerzyworks/Masterfile
What’s a Bug?
Many people use the word “bug” to mean any kind of insect or other small crawling creature, such as a spider or worm. (That’s how we use the word in this article.) But scientists and other experts use the word to mean only a certain kind of insect they call a “true bug.”
It’s a buggy, buggy world out there! Of all the animal species on Earth, 9 out of 10 may be insects. And, as you know, some insects can behave badly: They bite. They sting. They spread germs. They eat our food—and even our homes!
But don’t let that scare you. Believe it or not, only a few kinds of insects do us any harm. In fact, most are good guys! Insects deserve a much better reputation. Read on and find out why.
Bugs Battle the Bad Guys
To farmers and gardeners, some insects can be real pests. Aphids, caterpillars, grasshoppers, and others love to eat the plants people grow for food or fun. And keeping these pests under control is a tough job. Good thing there’s a whole army of insect-eating insects around.
Some insects are famous for munching huge numbers of pests. A ladybug, for example, may eat 500 aphids before it grows up! (Aphids harm plants by sucking out their juices.)
But many less-familiar “good guys” are out there doing their parts, too. The lacewing, in the large photo, above, for example, is about to chow down on some pesky green aphids. And that braconid (BRAK-uh-nid) wasp, in the small photo, above left, is doing another good deed. She’s laying eggs inside a tomato hornworm caterpillar.
Those little wasp eggs will cause the caterpillar big trouble! They will hatch into larvae that feast on the hornworm’s insides. No more chomping on tomato plants for this caterpillar!
But the story doesn’t end there. After a few weeks, each larva chews its way out of the caterpillar and spins a tiny, white cocoon. Soon the dying caterpillar is covered with cocoons (small photo, above right). Later, out of each cocoon comes an adult wasp. Then off they fly to find mates and start the cycle all over again. And that means still fewer hornworms to munch on tomato plants.
Here’s the best news: When bugs battle bugs, farmers and gardeners don’t need to use as much pest-killing poisons to protect their crops. That makes the Earth healthier for everyone.
Bugs Recycle Waste
Every day, all around the world, millions of tons of animal dung drop onto the ground. (Dung is just another word for poop.) You don’t even want to think about what would happen if all that poop kept piling up everywhere! One reason it doesn’t? Dung beetles.
When a dung beetle finds a fresh pile of poop, it breaks off a bit and presses it into a ball. Then it rolls the ball away (photo, above, right) and buries it. The dung beetle may save the ball to eat later. Or it may lay eggs in it. The eggs then hatch into grubs, which are surrounded by all the food that they need.
Dung isn’t the only thing that needs recycling. Think of all the leaves, dead branches, and even whole trees that fall in a forest every year. They’d pile up in a hurry, too, if it weren’t for millions of hungry creatures waiting on the forest floor.
Many of those creatures are insects such as roaches, earwigs, crickets, and beetles. Some eat the leaves, while others go for the wood. Inside a rotting log, for example, you may find large white grubs feasting away (photo, above, left page, top left). Those shown here are the larvae of a rhinoceros beetle (photo, above, left page, lower left)—one of the largest insects on Earth.
As these hungry insects munch away, they produce droppings. And soon those droppings become part of the rich forest soil.
Bugs Spread Pollen
How about a sweet, juicy apple for lunch? Without insects, there would be no such thing. There’d also be no oranges, plums, pears, peaches, watermelons, cantaloupes, berries, chocolate— or hundreds of other foods we love. (You’d also have to do without broccoli or Brussels sprouts, but you may not care as much about those!)
The insects that make these foods possible are called pollinators. They carry powder called pollen from one flower to another. The pollen fertilizes the flowers, which allows them to make seeds and fruit. Honeybees (photo, above, right page, top) and bumblebees are some of our best-known pollinators. But thousands of other kinds of insects, including some beetles (photo, above, right page, bottom), wasps, and flies, can be good pollinators, too.
Bugs Make Things
Honeybees make honey (photo, above, left page, lower left), which many people love to eat. And other insects make other things we can use.
One such product is silk. You may already know that spiders spin strands of silk to make their webs. But did you know that some caterpillars called silkworms also make silk? They use their silk to make cocoons before turning into moths. And it’s this silk that we use to create silk cloth.
In the photo (above, left page, top left) you can see some silkworms feeding on leaves. These silkworms are being raised in a silk farm. Next to them are the yellow cocoons that other silkworms have already made. People will gather the cocoons, take the silk thread from them, and turn it into beautiful, delicate cloth.
Another “productive” insect is a tiny, fuzzy bug called a cochineal (KAH-chuh-neel). Cochineals (photo, above, left page, middle right) live on prickly pear cactuses, sucking the plants’ juices. Long ago, people discovered that the female bugs produce a red chemical. Native peoples of Mexico still dye their clothing with it. And modern companies add the dye to lipstick, paint, pills, and even some kinds of food and drink. That’s right—when you eat red candy or drink red-colored juice, you may be gulping down chemicals made from the ground-up bodies
Bugs Help Scientists and Doctors
Insects have a lot to teach us. Termites, for example, construct huge nests with built-in “air conditioning.” By studying these amazing nests, scientists are learning how to cool our own buildings with less energy.
Scientists have also been studying how insects use their six legs to move around on rough ground. (Insects are champs at this.) And now scientists are using what they learn to build better robots (photo, above, right page, top) for exploring the rough surfaces of other planets.
Some insects help us stay healthy, too. For example, doctors may have a hard time getting people’s wounds to heal with just surgery and medicines. In those cases, it may be time to bring on the bugs!
Blowflies (photo, above, right page, middle) produce tiny maggots (larvae) that doctors place on troublesome wounds (photo above, right page, bottom). These maggots get right to work! They give off juices that digest dead or infected tissue and bacteria, turning it all into a kind of “soup.” That soup becomes the maggots’ food.
After a few days, the doctors remove the well-fed maggots,and the wound usually is then able to heal on its own.
Bugs Feed Animals & Us, Too!
Every second of every day of every year, countless insects are being gobbled up by countless other creatures. And this is the way it’s been for more than 300 million years.
Many kinds of animals eat nothing but insects. And many others eat them whenever they can. The European beeeater in the photo, opposite, below left is a full-time bug-muncher. It has caught a bumblebee, and now it’s tossing it like a piece of popcorn before swallowing it. The monkey-like tarsier in the photo, opposite, top right is chowing down on a katydid.
But animals aren’t the only insect-eaters. The boy in the photo, above, below right is about to gulp down two roasted stink bugs. They are considered a tasty treat in his Asian country of Indonesia.
And in many parts of the world, big, fat, juicy beetle grubs are a favorite snack. Why not? Insects are loaded with vitamins and minerals, they’re low in fat and high in protein, and many people claim they even taste good! Did someone just say “good”?
Well, then maybe that can be the final word on bugs!