. Elementary textbook of economic zoology and entomology. Zoology; Insect pests. SLIME SLUGS, MYRIAPODS AND INSECTS 151 It is in this stage that most of the radical changes in structure are undergone which are necessary to make the moth or butterfly out of the caterpillar, the house-fly out of the maggot, or the beetle out of the grub. However, most of these changes have their beginnings during the larval stage. For example, little wing buds have been developing all through the larval life, but they have remained very small and invisible underneath the chitinized cuticle of the larva. Especial
. Elementary textbook of economic zoology and entomology. Zoology; Insect pests. SLIME SLUGS, MYRIAPODS AND INSECTS 151 It is in this stage that most of the radical changes in structure are undergone which are necessary to make the moth or butterfly out of the caterpillar, the house-fly out of the maggot, or the beetle out of the grub. However, most of these changes have their beginnings during the larval stage. For example, little wing buds have been developing all through the larval life, but they have remained very small and invisible underneath the chitinized cuticle of the larva. Especially in the last few days of the larval stage are the various changes going on rapidly. But they are so radical in. FIG. 66.—Metamorphosis, complete, of Monarch butterfly, Anosia plcxippns. a, Egg (greatly magnified); b, caterpillar or larva; c, chrys- alid or pupa; d, adult or imago. (| natural size; after Jordan and Kellogg.) character that it is impossible for the insect to maintain an active food-getting life and make the changes at the same time. Hence comes the necessity for the quiescent pupal stage in which the insect, living on food stored up as fat by the larva, and safely inclosed in a hard protecting shell, can make the great changes necessary to its becoming a fully developed winged imago, different as to mouth-parts, eyes and antennae, different as to body shape, different as to legs and abdominal appendages, and, together with all these structural differences, radically different as to habits and behavior. Many of the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Kellogg, Vernon L. (Vernon Lyman), 1867-1937; Doane, Rennie Wilbur, 1871-. New York, H. Holt and company
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