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The characters, therefore', Which we have given, by which to know 

 an insect apply to the perfect state or imago alone and not to all stages 

 of its life. 



We have spoken of the transformations or changes the butterfly 

 undergoes as an illustration of the different stages of insect life, — first 

 there was the egg; second the caterpillar or larva; third the chrysalis 

 or pupa, during which it was quiet and in apparently a dormant 

 state; and fourth the perfect insect or imago ; all of these being very 

 distinctly marked in the life of the butterfly. But all insects do not 

 undergo such marked and distinct changes, in fact many can scarcely 

 be said to undergo any transformations, yet the terms larva, pupa and 

 imago, or perfect, are used to designate the corresponding stages in their 

 life. 



Take for example a common grasshopper as soon as hatched, though 

 diminutive in size, it has the form of the full grown or perfect insect, 

 wanting only the wings; it is now a larva; after a while it acquires 

 ,the rudiments of wings, it is now a pupa; but instead of changing 

 ',$&to a quiet and dormant chrysalis, it continues active , amir feeding as 

 voraciously as before ; after repeated moultings it acquires full and 

 complete wings (if it is a winged species) and is then a perfect insect. 



Such transformations or metamorphoses (another name for these 

 changes) as the butterfly undergoes, are called complete, because the 

 various stages are well marked; while those which the grasshopper 

 ; undergoes are called incomplete, as the different stages are not dis- 

 tinctly marked by different modes of life. The former, or complete, 

 is often designated by saying " the pupa is inactive;" the latter, or 

 incomplete, by saying " the pupa is active." 



If we trace the life history of a beetle, wasp, bee, butterfly, common 

 J fly, and many other insects, we shall find their transformations are 

 complete, while in all the rest they are incomplete, which furnishes us 

 one very important character by which to separate insects into differ- 

 ent groups or divisions, and assists in determining to which one of 

 ( these divisions a specimen belongs, while in the preparatory states,- 

 (that is, while a larva or pupa.) But as this character, to be useful, 

 .requires a knowledge of the entire life of the insect, we seek for such 

 (.characters a« it bears always with it in the perfect state. I will, 

 .therefore, proceed to give briefly those characters by which we deter- 

 mine the larger divisions of the class. 



If we examine the mouth of a beetle, wasp, bee, grasshopper, cock- 

 t roach, cricket and dragon fly, we will find that they have strong, 

 (horny jaws which open side wise. These strong jaws are called mandi- 

 bles, and all those species which possess them, mandibulate insects. 

 All species which do not have horny jaws, have the mouth drawn out 

 into a more or less elongated tube, sometimes horny and jointed as in 

 ithe squash bug, sometimes long, flexible and coiled as in the butter- 

 flies, and sometimes short, thick and fleshy, as in the common fly. 

 (Such mouths are evidently adapted to sucking and are, therefore, 

 •called Hamtellate and the species which possess them Haustellate in- 

 mects. This fact affords us a very distinct and easily observed charac- 

 ter by which we may separate all insects into two groups, or in other 

 words, the Class into two Divisions. But before making use of this 

 character, I will introduce certain terms used as the names of the, 



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