Forest entomology . Fig. 8.—Fully developed Tortoiseshcll Butterfly. (Flatters.) simply injurious in the larval stage alone. The perfect insect (orimago, as it is termed in entomology) often takes no food what-ever, except sipping water or juices, and the duration of life is oftenso short as to have become proverbial. As a branch of economic entomology, the student of forest insectsshould strive to ascertain where and when egg-deposition takes place, how long the insect remains inthe egg stage, how long beforethe first moult and between theother larval moults, when andhow long it remains in th
Forest entomology . Fig. 8.—Fully developed Tortoiseshcll Butterfly. (Flatters.) simply injurious in the larval stage alone. The perfect insect (orimago, as it is termed in entomology) often takes no food what-ever, except sipping water or juices, and the duration of life is oftenso short as to have become proverbial. As a branch of economic entomology, the student of forest insectsshould strive to ascertain where and when egg-deposition takes place, how long the insect remains inthe egg stage, how long beforethe first moult and between theother larval moults, when andhow long it remains in the pupalstage, and the time and appear-ance of the perfect insect — inshort, a full life-history. With regard to the structureof insects, it may be repeated,and must always be borne inmind, that an insect is a creature whose body is divided intothree parts—head, thorax, and abdomen. As a biological subject,insect anatomy and physiology is a very broad and interesting. Fig. 9.—Fully developed Tortoiseshell Butterfly.(Flatters.) INTRODUCTION. 9 one, inasmuch as serial section-cutting and the highest powers ofthe microscope must be employed. This, though highly inter-esting in itself, is certainly not of vital importance to the youngstudent of forest entomology. It is, however, indispensable that thesalient features of head, thorax, and abdomen should in all cases bewell studied, and in some special instances be committed to is upon these points that generic and specific characters advanced student with a fair amount of leisure would do well tostudy the internal anatomy of insects. The head is theoretically composed of a number of pieces, but ingeneral appearance is made up of one piece. On the under side it
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