Forest entomology . Fig. 7.—Emergence of Tortoiseshell Butterfly more fully advanced. (Flatters.) of development, which is chiefly a question of wing expansion, takesat most only a few hours. 8 FOREST ENTOMOLOGY. In many cases where we have incomplete metamorphosis, the insectis injurious in all its respective stages, as, for instance, in Aphidseand Cicadae. On the other hand, when the metamorphosis is com-plete, we find the insect injurious in larval and perfect stages, or. Fig. 8.—Fully developed Tortoiseshcll Butterfly. (Flatters.) simply injurious in the larval stage alone. The perfect ins
Forest entomology . Fig. 7.—Emergence of Tortoiseshell Butterfly more fully advanced. (Flatters.) of development, which is chiefly a question of wing expansion, takesat most only a few hours. 8 FOREST ENTOMOLOGY. In many cases where we have incomplete metamorphosis, the insectis injurious in all its respective stages, as, for instance, in Aphidseand Cicadae. On the other hand, when the metamorphosis is com-plete, we find the insect injurious in larval and perfect stages, or. 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
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