32 SOME SOUTH INDIAN INSECTS. ETC. [CHAP. HI. 



always accompanied by a subsequent increase in size, is also 

 necessitated in order to get rid of the waste products of metabolism 

 induced by feeding and growth. 



The appearance of the immatun liters very 



considerably at each or any particular moult, especially in the case 

 Of caterpillars, in which the changes of colour and more particularly 

 in the arrangement of the tubercles and primary hairs have often. 



,'„-. 16 —Pupa of Eumenes conica (1) newly tun, '■ old, 



and (21 the same a week Later, showing developmi i 



I wasps, 

 the development of the individual thus epitomizing that of the i mal.) 



in the earlier stadia at least, a phylogenetic significance which is 

 of great importance in any natural system of classification. In a 

 few cases, especially amongst parasitic insects (Cantharid beetles, 

 Strepsiptera, etc.), we find more than three immature stages, due to 

 the development of more than one larval form ; this phenomenon is 

 called Hvpermetamorphosis. 



The time occupied by the metamorphosis of any particular 

 insect, that is to say, practically speaking, the life of a single genera- 

 tion is very variable and may extend from a couple ot week- to 

 twenty years. An average period in Southern India is probabh 

 lDO ut two months though manj pests pass through a generation in 

 a month or less. Some insects may delay metamorphosic changes 

 until the advent of suitable climatic conditions and this may occur 

 in either of the passive (oval or pupal) stages. 1 tms the eggs may 

 retain their vitality until stimulated by an influence such a- 

 moisture, as in the ca nosquitos of the genus Stegomyia 



in which the eggs retain vitality for months in ad 

 dition (such as normally occurs duringthe dry weather precedinj 

 monsoon in the localities hollow, in tree-trunk-, etc.-in winch 

 thej ire deposited), batching out when exposed to humidity. 1 his 

 is perhaps the case also with some grasshoppers. < >r the eggs may 

 not hatch out all at once, but a few individuals ol each batch may 

 emerge at intervals .luring a period of several months (as m the 

 case of Orgyia antiqua) thus ensuring thai some at least may meet 



