i II \r. in. | METAMORPHi »S 27 



Chapter III. 

 METAMORPHOSIS. 



■• Fhere is a tlirTerencj betweea a grub and a butt 1 >ui was a grub.'' 



Shakespeare. 



[NSECTS, like most other animals, commence their existence in 



the egg stage and before attaining the adult state undergo a series 

 of changes which art- more exactly expressed by the term metamor- 

 phosis. In the more primitive and generalized forms, ot which the 

 Fish Insect may be taken as a type, the amount of metamorphosis 

 undergone is comparatively slight, the newly-hatched insect 

 differing in little except size from the adult. In the case of a 

 grasshopper, the metamorphosis undergone is also slight, but the 

 adult differs from the young in possessing wings, although some 

 grasshoppers are wingless even in the adult stage. In the more 

 specialized groups of insects, however, the changes between the 

 newly-hatched young and the adult insect are not only consider- 

 able but they are abruptly separated b\ a third Stage, different from 

 that which precedes and follows it, in which the insect undergoes a 

 period of quiescent inactivity during which it is known as a 

 " pupa." ( )f this last group we niaj cite a butterfly as an example. 

 It may be rioted as a genera] rule that insects with slight metamor- 

 phosis usually grow very slowly, whilst those with a pupal stage 

 often complete a generation in a very short period of time, and that 

 (spi aking very generally and bearing in mind that all existing 

 insects are equally far removed in point of time from any common 

 ancestor, although, as pointed out above, the more specialized 

 insects may be so remo\ ed bj a greater number of generations than 

 the unspecialized) insects with little metamorphosis are less special- 

 ized and approach closet on the whole to the more primitive types 

 of insects than do those with considerable metamorphosis. 



The various orders of insects with much or little metamorphosis 

 shown in the table on pages 2021, but it may be useful to 

 compare here the lifehistory of a Butterfly and a Grasshopper, as 

 a t \ pe "i each class. 



