Good Bugs & Bad Bugs Student Booklet Molly Keck Program Specialist – Urban IPM 3355 Cherry Ridge, Suite 212 San Antonio, Texas 78230 Phone: 210-467-6575 Email: [email protected] Words Abdomen Entomology Entomologist Exoskeleton Thorax Lesson 1 - Entomology Reading Exercise Entomology is the study of insects. An entomologist is a scientist who studies insects. Insects are arthropods. They are related to other arthropods such as spiders, scorpions, shrimp, millipedes and centipedes. Insects are different from other arthropods because they have three body regions, six legs, one pair of antennae, and two pairs of wings. The three body regions of an insect are the head, thorax, and abdomen. An insect’s head contains eyes, mouthparts and antennae. Insect antennae are feelers that help the insect feel, hear, smell, and taste. The thorax is the middle of the insect’s body and is the locomotion part of an insect. The legs and wings are attached to the thorax. Not all insects have wings, but they can have up to two pairs (or four) wings. The abdomen is the hind part of the insect. If an insect has a stinger, the stinger is on the abdomen. Insects and other arthropods have an exoskeleton; their skeleton is on the outside of their body. It acts as armor and protects the insect. This is why beetles are so hard and why some insects crunch when you step on them. Legs Antennae Head Thorax Abdomen WingsQuestions 1. How do you know an insect is an insect and not another animal? 2. What are the body regions of an insect? 3. Why are insect’s bodies so hard? 4. What is an entomologist?Glossary Words Complete Metamorphosis Incomplete Metamorphosis Metamorphosis Molt Lesson 2-1 – Insect Lifecycles Reading Exercise A: Metamorphosis is a change in form. Insects go through metamorphosis to eventually become adults. Many insects completely change their size, shape and color as they go through their lifecycle. All insects start out as eggs. The egg hatches, and the insect goes through a series of molts until it becomes an adult. When an insect molts, it sheds its exoskeleton (or skin) and waits for a short period of time until its new exoskeleton becomes hard again. The insect’s body gets bigger inside this exoskeleton, and eventually it must be shed in order to let a new, larger one form. Only the immature insects can molt. Once an insect becomes an adult it will no longer molt, it is essentially done growing. One way to tell the difference between adult insects and the immature stages is to see if the insect has wings. Only adult insects have fully developed, functional wings. If you see a small fly it is incorrect to call it a baby fly, because that is as big as it will ever get! There are three different categories for the types of metamorphosis present in insects. Very primitive insects have no metamorphosis in that there is no important change in form as the insects get older. More advanced insects undergo either incomplete metamorphosis or complete metamorphosis. Immature stages of insects with incomplete metamorphosis usually look very much like smaller versions of the adults, only their wings are either completely absent or very small and not developed. Immature stages of insects with complete metamorphosis always look very different from the adults. The type of metamorphosis depends on the group of insects. For example, all cockroaches have incomplete metamorphosis. All butterflies have complete metamorphosis. Questions: 1. What are the two types of metamorphosis more advanced insects go through? 2. What does metamorphosis mean? 3. What is one way to know if an insect is an adult? 4. Does an insect molt again once it is an adult?Glossary Words Incomplete Metamorphosis Lesson 2-2 – Incomplete Metamorphosis Reading exercise B: Incomplete metamorphosis has only three different life stages: Egg, nymph, and adult. When an egg hatches, a nymph emerges. The nymph is similar to the adult, but is smaller and never has fully developed wings. Immatures are called nymphs if they live on land and sometimes called naiads if they live in water. Really though, naid is just a word for an aquatic nymph present in some groups of insects. A nymph molts a number of times before it becomes an adult. Each time the nymph molts its wing pads grow larger and larger. Finally, on the last molt, the adult emerges from the shed exoskeleton. The adult has fully developed wings, not wing pads. Both the adults and nymphs have the same type of mouth parts and therefore eat the same types of food. Nymphs usually eat more food so that they can get enough nutrients to become a healthy adult. Some common insects that have incomplete metamorphosis are grasshoppers, cockroaches, preying mantises, stink bugs, and other true bugs. Praying Mantis Ootheca (egg case) Praying Mantis Adult Questions: 1. What are the life stages an insect that has incomplete metamorphosis goes through? 2. What are some other names for the immature stage of an insect that goes through incomplete metamorphosis? 3. Name some insects that go through incomplete metamorphosis.Glossary Words Complete Metamorphosis Larva Molt Pupa Lesson 2-3 – Complete Metamorphosis Reading Exercise C: Complete Metamorphosis has four different life stages. Egg, larva, pupa, and adult. An egg is laid, and a larva hatches from the egg. A larva is called many different things depending on the insect. Butterfly and moth larvae are called caterpillars; beetle larvae are sometimes called grubs; and fly larvae are sometimes called maggots. Larvae molt a series of times, growing each time. Because insects are covered by an exoskeleton (even larvae and pupae) they must shed their exoskeleton to grow. Humans have their skeletons in the inside of their bodies and our skin stretches when we grow. Insects cannot do that, so they must shed their skin, or exoskeleton, and then grow. A larva will molt several times before it is ready to become a pupa. The last larval stage will make a pupal case to protect the pupa from the environment. Butterfly pupal cases are called cocoons or a chrysalis. The pupa is sometimes called the resting stage of an insect because it usually does not move. But there is a lot of activity going on inside the pupal case. The pupa is preparing to become an adult, forming wings, changing mouthparts, and gaining new organs! When the adult emerges it