318 TEXT-BOOK OF ZOOLOGY 



as they live under the same, or at leaet similar, or under quite dissimilar 

 conditions of life (see grasshopper and cabbage butterfly). In the latter 

 case a period of quiescence intervenes in the course of the metamorphosis, 

 during which great and important changes take place. In this, the 

 so-called pupa stage of its development, the animal is, as a rule, perfectly 

 motionless, and consequently incapable of taking food. During this 

 period the pupa lives upon the stores of material which are accumulated 

 in the body during its larval existence. The metamorphosis in this case 

 is described as complete ; when no pupa stage is interposed in the course 

 of development it is known as incomplete (give examples). When is the 

 larva termed caterpillar, false caterpillar, or maggot? (See cabbage 

 butterfly, sawfly, and bee.) 



ORDER I.: SCALE-WINGS (LEPIDOPTERA). 



Mouth parts suctorial, forming a spirally coiled-up trunk. All the 

 thoracic somites coalescent. Anterior and posterior wings similar, 

 membranous, covered with scales. Metamorphosis complete. 



A. Maceolepidopteea. 



Sub-Order i : Butterflies (Rhopalocera). 



The Large White Cabbage Butterfly (Pieris brassica). 



(Breadth 2 to 2\ inches.*) 



A. The Egg. 



If we watch the white cabbage butterflies in July and August, when 

 they flutter in greatest abundance about our fields and gardens, we shall 

 probably notice some one or other of tbese merry insects alighting upon 

 the under surface of a cabbage leaf. The insect in question is a female, 

 which, as we shall be able to convince ourselves in a few minutes, has 

 laid upon the leaf a small cluster of golden yellow eggs. Of these eggs 

 she lays from 200 to 300 gradually. Certainly a very respectable 

 number, and yet by no means excessive when we consider how many of 

 the insect's progeny are destroyed by its numerous enemies, or by the 

 weather, either in the larval, pupal, or butterfly stages (compare with 

 rodents, frog, carp, etc.). 



The insect selects the under side of the leaf for its delicate eggs, 

 because there they are protected against rain and the parching effect of 

 the sun's rays, and also hidden from the eyes of birds and ichneumon 



* Breadth is reckoned from tip to tip of the expanded front-wings. 



