4 GRAMMAR OF ENTOMOLOGY. 



the grubs, when full grown, become for a time 

 motionless ; their skin opens, and from it comes 

 forth the perfect insect, which has four wings, 

 and which does not increase in size. 



3. In a very great number of insects, the grub 

 changes its skin, and completely alters its form on 

 becoming motionless ; indeed, almost as great a 

 change in appearance takes place, as in the change 

 from the grub to the perfect state ; when this is 

 the case, the motionless state is called the chry- 

 salis. 



4. Thus we have four stages in the life of an 

 insect, four states which it is necessary thoroughly 

 to understand ; the egg (ovum) which is motion- 

 less, and apparently lifeless ; the grub (larva), 

 which is active, but without wings, voracious, and 

 grows rapidly ; the chrysalis (pupa), which is quite 

 motionless, and which does not occur in all in- 

 sects ; the perfect insect (imago), which is active, 

 has wings, does not grow, and which, by laying 

 eggs, perpetuates its kind. 



5. The names egg, larva, pupa arid imago, are 

 the terms generally employed in descriptions ; the 

 three last answer equally well for Latin or Eng- 

 lish, but it must be borne in mind that the words 

 grub, maggot, and caterpillar, are synonymous 

 with the term larva ; and perfect insect, fly, &c. are 

 synonymous with the term imago ; and the English 

 and Latin words are used in English descriptions 

 almost indifferently. 



