INSECTS
a perfect insect, while the immature adult cicada goes over into the fully mature form quickly and without a molt.
We may conclude, therefore, that the pupa of insects with complete metamorphosis corresponds with the immature stage of the adult in insects with incomplete metamorphosis.
This idea concerning the nature of the insect pupa has
Fig. 141. Showing the resemblance of the pupa of an insect with complete metamorphosis to the immature adult
form of an insect with incomplete metamorphosis
A, immature adult cicada, taken from the last nymphal skin. B, immature pupa of a moth, taken from the last larval skin. C, the mature pupa of a wasp
been well expressed and more fully substantiated by E. Poyarkoff, and it appears to have more in its favor than the older view that the pupa corresponds with the last nymphal stage in insects with incomplete metamorphosis. According to Poyarkoff's theory, the pupa has no phylogenetic significance, that is, it does not represent any free-living stage in the evolution or ancestral history of insects; it is simply a prolonged resting period following the shedding of the last larval skin, which terminates with an added molt when the adult is fully formed.
It frequently happens that a pupa has some of the adult characters better developed than has the adult itself. The pupae of insects that
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