INTRODUCTION. 7 



instance, the young grasshopper comes from the egg a wingless 

 insect, and consequently unable to move from place to place, in 

 any other way than by the use of its legs ; as it grows larger it 

 is soon obliged to cast off its skin, and, after one or two moult- 

 ings, its body not only increases in size, but becomes proportion- 

 ally longer than before, while little stump-like wings begin to 

 make their appearance on the top of the back. After this, the 

 grasshopper continues to eat voraciously, grows larger and larger, 

 and hops about without any aid from its short and motionless 

 wings, repeatedly casts off its outgrown skin, appearing each time 

 with still longer wings, and more perfectly formed limbs, till at 

 length it ceases to grow, and, shedding its skin for the last time, it 

 comes forth a perfectly formed and matured grasshopper, with the 

 power of spreading its ample wings, and of using them in flight. 



Hence theie are three periods in the life of an insect, more or 

 less distinctly marked by corresponding changes in the form, pow- 

 ers, and habits. In the first, or period of infancy, an insect is 

 technically called a larva, a word signifying a mask, because 

 therein its future form is more or less masked or concealed. 

 This name is not only applied to grubs, caterpillars, and maggots, 

 and to other insects that undergo a complete transformation, but 

 also to young and wingless grasshoppers, and bugs, and indeed 

 to all young insects before the wings begin to appear. In this 

 first period, which is generally much the longest, insects are al- 

 ways wingless, pass most of their time in eating, grow rapidly, 

 and usually cast off their skins repeatedly. The second period, 

 wherein those insects, that undergo a partial transformation, retain 

 their activity and their appetites for food, continue to grow, and 

 acquire the rudiments of wings, while others, at this age, entirely 

 lose their larva form, take no food, and remain at rest in a death- 

 like sleep, — is called the pupa state, from a slight resemblance 

 that some of the latter present to an infant trussed in bandages, as 

 was the fashion among the Romans. The pupae from caterpillars, 

 however, are more commonly called chrysalids, because some of 

 them, as the name implies, are gilt or adorned with golden spots ; 

 and grubs, after their first transformation, are often named nymphs, 

 for what reason does not appear. At the end of the second 

 period insects again shed their skins, and come forth fully grown, 

 and (with few exceptions) provided with wings. They thus enter 



