OUTDOOR KIDS: Is It An Insect?

By Kelton Hatch, Idaho Department of Fish & Game They are on the ground, in trees, in soil and in your house. They make up about 80 percent of all known animal species on Earth. Insects are all around us. They are common in every habitat except the ocean. Sometimes any small creepy crawly is called a bug or insect, but not every small creeping thing is an insect. To be an insect, an animal must meet three important rules. They must have three main body parts - the head, thorax and abdomen, six legs and two antennae. The head of an insect has the eyes, antennae and mouthparts on it. Insects have two large compound eyes. Compound eyes are faceted. They have more than one lens or surface. Compound eyes look a bit like a honeycomb. Insects may also have up to three simple eyes. You have simple eyes. A simple eye has one surface or facet. Without moving their heads, many insects can see in every direction around them. Insect antennae are used for touching, smelling and sometimes hearing. The mouthparts of insects are made to suck or to chew depending upon the insect and what it eats. The thorax, or middle part of an insect, is where the wings and legs are found. All adult insects have legs, but not all insects have wings. Mosquitoes have four wings. The two front wings are used for flying and the back wings help the mosquito to keep its balance in the air. The abdomen is where an insect breathes. Most insects breathe through tiny holes called spiracles. Insects that live in water would drown if they had spiracles. Some aquatic insects breathe with gills like a fish. Other insects come up to the surface of the water and grab a bubble of air or stick a breathing tube above the water. Insects do not have an internal skeleton of bone like you. Insects have an exoskeleton. An exoskeleton is a hard fingernail-like covering on the outside of the insect's body. The exoskeleton is divided into separate pieces called plates. The plates fit together like a puzzle and are held together with soft flexible membranes. The membranes work like rubber bands. They allow the insect to move its body and let the insect's abdomen grow while it eats. The exoskeleton can flex but not expand. As insects grow, their exoskeletons become too small. They shed their exoskeletons when they outgrow them. Just like a snake sheds its skin. Insects come in all shapes and sizes. Hairy winged beetles are some of the smallest of insects. They can crawl through the eye of a needle. Fairyflies are also small. They can fly through the eye of a needle. The longest insect is a 13-inch long walkingstick found in Malaysia. Atlas moths in India have the largest wings at 12 inches across. Goliath beetles found in Africa are the bulkiest and heaviest. They can be as big as a baseball. Kelton Hatch is a regional conservation educator for the Idaho Department of Fish and Game.