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Unit1ThePerfectSwarmNarrator:Damagefromswarmsoflocustscanreachdisastrousproportions.Asingleswarmofdesertlocustscanconsumeover70,000metrictonsofvegetationaday.Thereis,however,onecontinentthat’slocust-free:NorthAmerica.旁白：蝗虫群的伤害可以达到灾难性的程度。一个单一的沙漠蝗虫可以消耗超过70000吨的植被一天。然而，有一个大陆是蝗虫自由：美国北部。Interestinglyenough,thiswasn’talwaystrue.Forhundredsofyears,theRockyMountainlocustwasacommonpestintheAmericanWest.Backinthemid-1800s,thousandsofpioneersjourneyedacrosstheU.S.insearchoffreelandandnewopportunities.Theysettledonthefrontierofthewesternstates,andbegantofarmthelandintensively,growingcornandothercrops.有趣的是，这并不总是真实的。几百年来，落基山脉的蝗虫是美国西部的一种常见害虫。早在19世纪中叶，成千上万的先驱者跨越美国在自由的土地和寻找新的机会。他们定居在西部边境，并开始对土地进行集中耕种，种植玉米和其他农作物。Then,in1875,outofnowhere,ararecombinationofaircurrents,drought,andbasicbiologyproducedtherightconditionsforanunthinkableevent,theworststormeverrecorded,the“perfectswarm.”Itcameoverthehorizonlikeastrange,darkcloud.Notmillions,notbillions,buttrillionsofinsects,sweepingthroughthelandlikealivingtornado.Thosewhosawtheincredibleeventandsurvivedneverforgotwhattheywitnessed.然后，在1875，走出无处，一个罕见的组合，空气电流，干旱，和基本生物学产生了正确的条件为一个不可想象的事件，最坏的风暴有史以来，“完美的群”，它在地平线上像一个奇怪的，黑暗的云。不是上百万，不是数十亿，而是数以万亿计的昆虫，像一个活生生的龙卷风席卷过大地。那些看到了令人难以置信的事件，并幸存下来的人从来没有忘记他们见证了什么。TheswarmcametogetheroverthestateofTexas,andsoonmovedquicklyacrossthefrontierinahugedestructivecloudthatwasnearly3,000kilometerslong.ThestormspreadnorthtowardsNorthDakota.ThelocustseventuallywentasfarwestastheRockyMountains,leavingapathofdevastationanddestructionwherevertheywent.群聚在德克萨斯州的上空，并很快在一个巨大的破坏性的云，是近3000公里长的边界迅速移动。风暴向北到了北。蝗虫最终在落基山脉的西部，离开了一条破坏性的道路和毁灭的道路。Anaccountfromonepersonwhoobservedtheswarmdescribedthelocuststorm.Thelocustscamedownfromtheskylikehail.Frightenedpeopleranscreamingintotheirhomesasthelocusts’clawsdugintotheirskinandhungupontheirclothing.Theyheardsharpcracksastheinsectscameunderfoot.Thelargelocustswereeverywhere,lookingwithhungryeyesturningthiswayandthat.Theirbodiesblockedthesun,bringingdarknessalongwiththedestruction.一个来自一个人的帐户，观察到群描述了蝗虫风暴。蝗虫从空中落下如冰雹。当蝗虫的爪子被挖进他们的皮，挂在他们的衣服上时，吓得人们尖叫着进入他们的家里。随着昆虫来踩在脚下他们听到尖锐的裂缝。大蝗虫到处都是，看着饥饿的眼睛转动着这样的方式。他们的身体挡住了太阳，带来了黑暗与毁灭。Cropdamageswereabsolutelyastonishing.IfsuchdestructionweretohappentodayitwouldcostanestimatedUS$116billion,morethanthemostcostlyhurricaneinAmericanhistory.Andthen,somethingremarkablehappened:theRockyMountainlocustsimplyvanished.农作物的损害是绝对惊人的。如果这样的破坏将发生在今天，它将花费大约116美元，超过了美国历史上最昂贵的飓风。然后，一些非凡的事情发生了：落基山脉的蝗虫简直就消失了。AttheUniversityofWyoming,entomologistDr.JeffLockwoodhasspentoveradecadeinvestigatingwhytheRockyMountainlocustdisappeared.在怀俄明大学的昆虫学家杰夫博士，她已经花了超过十年调查为什么落基山蝗虫消失。Dr.JeffLockwood,UniversityofWyoming:“Therewereprobablymorelocustsinthela...