100 INTRODUCTION TO ZOOLOGY. 



in the eyes is more than counterbalanced by the abundance in 

 which these organs are bestowed. 



No one circumstance connected with insects, has perhaps 

 arrested the attention of ordinary observers so much as what 

 is termed their metamorphoses. The vertebrate animals retain 

 through life, with some variations in size and colouring, very 

 much the same forms which they had at birth. Insects, on 

 the contrary, pass through four states of existence, and these 

 are in general distinctly marked (Fig. 73). They are first 

 contained in eggs, which are deposited by the parent in 

 suitable situations, and with a degree of instinctive care which 

 fills us with admiration. They then become active and 

 rapacious, and are well known by the names of grubs, maggots, 

 and caterpillars, according to the tribes to which they belong 

 (Fig. 77). To this condition Linnasus applied the Latin word 

 larva (a mask), as if the perfect insect were masked or con- 

 cealed in the figure of the Caterpillar. The ravages of which 

 the forester and the gardener complain, result most generally 

 from the voracity of insects in their larva state. They eat 

 much, increase rapidly in size, change their skin several times, 

 and pass into another state, in which, in some tribes, all 

 appearance of vitality is for a time suspended. The Caterpillar 

 of the Butterfly or Moth, when the period for this change 

 arrives, seeks out a secure asylum for its period of helpless- 

 ness, and suspends itself by a thread (Figs. 74, 78), envelopes 

 itself in silk, makes a covering of leaves, or entombs itself in 

 the earth, according to the habits of the species. Some of 

 them in this state appear, on a miniature scale, like Egyptian 

 mummies, or like an infant wrapped up in swaddling-clothes. 

 From this peculiarity the term pupa (a baby) has been given 

 to them ; and chrysalis, a word of Greek origin, referring to 

 the bright or golden colours which some of them display, has 

 also been applied. We shall use the terms pupa and chrysalis 

 indifferently, meaning, in all cases, the insect in the form it 

 has prior to its appearance in the last and perfect form ; that 

 which is termed the Imago (Figs. 75, 79), as though it had 

 not until then its perfect or fully developed image. All insects, 

 however, do not assume the quiescent state of those just 

 mentioned. The young of the common Gnat (Fig. 76) pass 

 the early stages of their existence as inhabitants of the water, 

 jerking about with great agility, or swimming with ease and 

 swiftness. The Crickets and Cockroaches are as active and 



