考研作文Sparethatspider不要伤害蜘蛛
Why,youmaywonder,shouldspidersbeourfriends?Becausetheydestroysomanyinsects,andinsectsincludesomeofthegreatestenemiesofthehumanrace.Insectswouldmakeitimpossibleforustoliveintheworld;theywoulddevourallourcropsandkillourflocksandherds,ifitwerenotfortheprotectionwegetfrominsect-eatinganimals.Weowealottothebirdsandbeastswhoeatinsectsbutallofthemputtogetherkillonlyafractionofthenumberdestroyedbyspiders.Moreover,unlikesomeoftheotherinsecteaters,spidersneverdotheleastharmtousorourbelongings.
Spidersarenotinsects,asmanypeoplethink,norevennearlyrelatedtothem.Onecantellthedifferencealmostataglance,foraspideralwayshaseightlegsandaninsectnevermorethansix.
Howmanyspidersareengagedinthisworkonourbehalf?OneauthorityonspidersmadeacensusofthespidersinagrassfieldinthesouthofEngland,andheestimatedthatthereweremorethan2,250,000inoneacre;thatissomethinglike6,000,000spidersofdifferentkindsonafootballpitch.Spidersarebusyforatleasthalftheyearinkillinginsects.Itisimpossibletomakemorethanthewildestguessathowmanytheykill,buttheyarehungrycreatures,notcontentwithonlythreemealsaday.IthasbeenestimatedthattheweightofalltheinsectsdestroyedbyspidersinBritaininoneyearwouldbegreaterthanthetotalweightofallthehumanbeingsinthecountry.