Insects by Cindy Grigg

Insects By Cindy Grigg 1 Like you, insects are alive. Both people and insects are animals. Insects are different from most other animals. Let's read to find out how they are different. 2 Insects are invertebrate animals. That means they have no backbone. Insects are the largest group of animals on Earth. In fact, about half of all animals that scientists know are insects! 3 Insects have three main body parts. They are the head, the thorax, and the abdomen. They have six legs. Many adult insects also have wings. The wings and legs are attached to the thorax. 4 Some invertebrate animals look like insects, but they are not. Spiders and scorpions, for example, are commonly confused with insects. Spiders and scorpions are not insects because they have eight legs, not six. They also have only two body segments instead of three. 5 Most insects lay eggs. Some young insects look like their parents. Other young insects, such as caterpillars, look very different from their parents. 6 All the stages in the life of an animal make up the animal's life cycle. Butterflies have a four-stage life cycle. Butterflies often lay eggs on leaves the insects can eat after they hatch. The egg is the first stage of the butterfly's life cycle. 7 When the egg hatches, a larva comes out of the egg. We often call the larva a caterpillar. This is the second stage. The caterpillar looks very different from the adult butterfly. The larva eats the leaves and grows very quickly. 8 After the larva grows big enough, it makes a hard covering for itself. This stage is called the pupa. Inside the hard covering, the pupa changes body form again. 9 Finally, the hard case around the pupa splits open. A butterfly comes out. The adult is the fourth stage of the butterfly's life cycle. The new adult butterfly's wings are wet when it comes out of the pupa. After the wings have dried, the adult butterfly flies away. 10 This change of body form in different stages of the life cycle is called metamorphosis. Butterflies have complete metamorphosis (four stages). Some insects have incomplete metamorphosis (three stages). 11 An insect that has incomplete metamorphosis is the fly. A fly lays eggs. The egg is the first stage. The egg hatches into a larva that we call a maggot. That is the second stage. Then the larva changes into a fly that looks like the adult. That is the third stage. 12 Insects don't have bones inside their bodies as you do. Instead, they have a hard outside shell. This is called an exoskeleton. This means a skeleton outside the body. It protects the insect's body like armor. When the insect grows, it needs a bigger exoskeleton. The old covering splits open, and the insect crawls out. This process is called shedding or molting. 13 Its new exoskeleton is still soft. It takes a while to harden. A young insect molts several times during its life cycle. This is not like metamorphosis because the insect doesn't change its body form. 14 Insects are an important part of our world. Many insects are useful to people. For example, bees carry pollen from plant to plant. Then the plants can form seeds. People eat many of these plants. Some bees also make honey that people use for food. Some insects, like ladybugs, eat other insects that damage plants and crops. Copyright © 2012 edHelper Name _____________________________ Science Pd: ___________________ Insects 1. How many main body parts do insects have? 2. How many legs do insects have? Four Six One Four Two Two Three Eight 3. The wings and legs are attached to which 4. All insects have the same life cycle. main body part? False Abdomen True Head Tail Thorax 5. How many stages are in the life cycle of the 6. How many stages are in the life cycle of the butterfly? fly? Two One One Four Three Three Four Two 7. Insects have a skeleton inside their bodies 8. What is the big word for an insect's hard just as people do. outside covering? False True .

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