Forest entomology . a differentcolour, and again commences feeding. Thisprocess is known as moulting, and occursseveral times during the larval stage until fullgrowth is reached. The duration of larvallife in arboreal insects is very varied some cases the period occupies only a fewdays, in others several years. The pupa, or third stage of the life of aninsect, is a period of rest or quiescence, whenthe insect takes no food. It is the period ofquiet transformation, when the ugly crawlingcaterpillar is being transformed into the beauti-ful moth, or the carrion maggot into the swiftairy
Forest entomology . a differentcolour, and again commences feeding. Thisprocess is known as moulting, and occursseveral times during the larval stage until fullgrowth is reached. The duration of larvallife in arboreal insects is very varied some cases the period occupies only a fewdays, in others several years. The pupa, or third stage of the life of aninsect, is a period of rest or quiescence, whenthe insect takes no food. It is the period ofquiet transformation, when the ugly crawlingcaterpillar is being transformed into the beauti-ful moth, or the carrion maggot into the swiftairy fly. The pupal forms and habits of forestinsects are very varied. Thus in beetles all theparts of the future insect are visible, saw-fliesand moths form cocoons, and the two-wingedflies form cases. Some descend into the groundto pupate, while others form hard cases on the food-plant. Fig. 4 maybe considered, for general purposes, as a typical pupa. The stages thus referred to—viz., egg, larva, and pupa—are the. Fig. 4.—Typical pupal formof an insect. (Platters.) INTRODUCTION. periods of growth and development. As soon as bursting from thepupal case takes place, the creature is then literally the perfect insect,inasmuch as there is no further change or development. It is well tobear this in mind, as it is a popular notion amongstcertain people not conversant with natural history j that small moths and flies are simply young , however, is not the case, for while there isoften a difference in size amongst individuals^ ofthe same species, it should be remembered thatno growth takes place after full pupal demonstration of this, perhaps a typical casemay be taken—viz., that of the Small TortoiseshellButterfly, Vanessa urticce. Fig. 5 represents thepupal case. In fig. 6 we have a representation ofthe first emergence from the pupal case ; in fig. / Fig. 5.—Pupal case ofSmall TortoiseshellButterfly (Vanessaurtica-). (Flatters.) 7, which is later,
Size: 1012px × 2468px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisheredinburghwblackwoo
