如何用英文描述昆虫生活史

如何用英文描述昆虫生活史
如何用英文描述昆虫生活史

如何用英文描述昆虫生活史
All but a few insects begin their lives as eggs (a few are born alive).Then from the egg,a small immature insect emerges.Depending upon the group to which it belongs,it will be either a larva or a nymph,but it may be called by various names.For instance,the larvae of the familiar butterflies and moths are often called caterpillars.Larvae of flies are called maggots,those of some beetles are grubs,and juvenile mosquitoes are known as wrigglers."Baby" bugs,which closely resemble their parents in miniature,are just called nymphs.
Crawlers are the pinpoint-size nymphs of scale insects.The aquatic nymphs of dragonflies are known as naiads.As the immature larva or nymph feeds and grows,it enlarges by shedding its rigid outer skin called an exoskeleton.Every time it does this it changes to a new stage called an instar.The first instar emerges from the egg and deve lops to the first molt.The last instar develops into the adult in simple development,or into the pupa in complex development .
Most common insects have 3 to 6 instars.Suppose you choose to study a moth that feeds on a tree or shrub.Because it is a moth,the insect has a type of complex development called complete metamorphosis.This simply means that during each generation the insect develops through four major stages--the egg,larva (caterpillar),pupa,and adult moth as in fig.1.A complete life cycle,then,should account for all these stages,and it will also include the several larval stages or instars.
Let's assume you locate a cluster of moth eggs on a study tree and plan to start the cycle with them.If possible,leave the eggs on the tree until the larvae begin hatching.This way the food will be in the correct stage to support the young larvae.Then transfer the insects and their food (leaves) to a wide-mouth jar,cover the opening with a cloth,and seal with a rubber band.You can study the general life cycle in the jar,but to learn the number of instars,you~ll need to isolate several insects and their food into baby food-type jars (one larva per jar).You may see them shedding their skins occasionally,but the best way to count instars is to remove the debri 5 every 4 to 5 days and search for cast skins.Each time you find a cast skin you can be certain a larva has changed to a new instar,and you will know how many instars there are when the larva transforms to the pupa.
To complete the life history study,you'll need to record the dates that each stage of the life cycle is present in its habitat.Generally,observations 3 to 5 days apart while it is growing are satisfactory for an insect with one generation each year.Also,be sure to determine the stage in which the insect overwinters.
要完成生活史的研究,你需要记录的日期,每个生命周期阶段是在其栖息地存在.一般来说,观察3至5天外,而它的增长是令人满意的一代与每年的昆虫.此外,一定要确定阶段,昆虫越冬.