2 HE METAMORPHOSIS OF INS.iCTS 



175 



e. GRADUAL METAMORPH ) IS 



{Paurometaboloits* Development) 



In several orders of insects there exists a type of development that 

 is characterized by the fact that the young resemble the adult in the 

 general form ot the body and in manner of life. There is a gradual 

 growth of the body and of the wing rudiments and genital appendages. 



Fig. 194. — Nymph of Mela- 

 noplus, first instar (After 

 Emerton). 



Fig. 195. — Nymph of Mela- 

 noplus, second instar 

 (After Emerton). 



Fig. 196. — Nymph of Melano- 

 plus, third instar (After Emer- 

 ton) 



Fig, 198. — Nymph of Melano- 

 plus, fifth instar (After Emer- 

 ton), 



Fig. 197. — Nymph of Melano- 

 plus, fourth instar (After 

 Emerton). 



Fig. 199. — Melanoplus, 

 adult. 



But the changes in form take place gradually and are not very great 

 between any two successive instars except that at the last ecdysis 

 there takes place a greater change, especially in the wings, than at 

 any of the preceding ecdyses. This type of metamorphosis is desig- 

 nated as gradual metamorphosis or paurometabolous development. 



The characteristic features oi paurometabolous development are 

 correlated with the fact that the mode of life of the young and of the 



*Paurometabolous : pauros (TraCpos), little; nietahole {fiera^o'Ki^)^ change. 



