精选文库Unit 1 The Perfect Swarm Unit 2 The Red Devils Unit 3 The Orient ExpressUnit 4 The Varied Cultures of China Unit 5 Afghanistans Heroic ArtistsUnit 6 Natachas Animal Rescue Unit 7 Firewalking Unit 8 Living in the Slow LaneUnit 9 Alternative Energy Unit 10 Mars on EarthGlossaryUnit 1This story is set in the central and western U.S., particularly in the states of Texas, Oklahoma, Kansas, Nebraska, North and South Dakota, and Wyoming as well as the Rocky Mountains.In the 1800s, the Rocky Mountain locust brought massive destruction to Western settlers. Then, the insects suddenly disappeared almost without a trace. Now scientists hope to find a reason for the locusts extinction. What caused the Rocky Mountain locust to disappear? Where will the scientists find the answers?I. Locusts! Read the paragraph. Then match each word with the correct definition. Many places in the world regularly experience plagues of locusts that can devastate entire countries. Locusts move in huge swarms, invade entire regions, and usually consume everything in their path. One swarm of locusts containing trillions of individual insects can eat thousands of tons of vegetation a day. Locusts are one of the worlds most destructive insects, but they themselves are sometimes destroyed. In the 1800s, for example, the Rocky Mountain locust mysteriously became extinct.1. plague _E_2. locust _G_3. devastate _C_4. swarm _E_5. trillion _A_6. vegetation _F_7. extinct _B_A.1,000,000,000,000B. no longer in existenceC. cause extreme damageD. any widespread cause of misery, suffering, or deathE. a large group, usually of insectsF. the plant covering an areaG. an insect noted for flying in large groups and destroying cropsII. The Rocky Mountain Locust Mystery. Read the paragraph. Then complete the definitions with the basic form of the underlined words or phrases. Dr. Jeff Lockwood is an entomologist who is particularly interested in the disappearance of the Rocky Mountain locust. The species was mysteriously wiped out in the late 1800s and there arent many clues as to why it happened. By studying locust specimens under a microscope and by taking DNA samples from the dead locusts, Lockwood aims to find out why the Rocky Mountain locust suddenly disappeared from Earth.1. a thing or fact that helps provide an answer to a question; evidence: clue2. a person who studies insects: entomologist3. an item that is an example of a larger group: specimen4. destroy completely; cause to no longer exist: wipe out5. a scientific instrument that uses lenses to make small objects appear larger: microscope6. the material that carries the genetic information in the cells of each living thing: DNASUMMARYThe mystery of the Rocky Mountain locust has baffled scientists in North America for over 100 years. After locusts completely devastated many parts of the United States in 1875, the entire species vanished from the continent. Entomologist Jeff Lockwood is determined to solve this mystery. After traveling to the Rocky Mountains and studying locusts frozen in glaciers, Lockwood begins to look at the mystery from a new angle.Warming upTeaching NOTES1.Show students some pictures of locusts from the reading passage or other sources you can find.2.Have students guess why the locusts in this video and the reading passage are called the perfect swarm.3.Ask questions like “ Have you ever seen a locust?” and “ What do you know about locusts?”Grasshopper There are hundreds of species of grasshoppers. These insects belong to the suborder Caelifera in the order Orthoptera, and have antennae that are almost always shorter than their bodies, and short ovipositorsorgans for laying eggs. Normally females are larger than males. Males have a single unpaired plate at the end of the abdomen. The two pairs of valves (triangles) at the end of the female abdomen are used to dig in sand by the female grasshopper when laying eggs. Although they differ in many features, they are easily confused with another sub-order of Orthoptera, Ensifera. The main distinguishing elements are the number of segments in their antennae and structure of the ovipositor. The location of the tympana and modes of sound production are other distinguishing features. Ensiferans have antennae with at least 2024 segments, and Caeliferans have fewer. Butterfly Like other holometabolous species with a complete metamorphosis where the immature insects are entirely different from the mature stages, butterflies life cycle goes through four stages: egg, larva, pupa and adult. Their wings are large, often brightly colored, and they have conspicuous, fluttering flight. Butterflies comprise the true butterflies, the skippers and the moth-butterflies. The very many other families within the order Lepidoptera are considered moths. Some butterflies