The Wonderful Ways of Insects and Spiders , [ 235 



to us than it was to our parents. Despite all the havoc that insects 

 wreak, they are actually of enormous value to us in some ways. 

 Insects play a vital role by pollinizing many plants on which 

 we depend for food for ourselves and our domesticated animals; 

 and many birds as well as fish would disappear if they were de- 

 prived of insect food. 



How Insects Develop 



THE MAGIC OF METAMORPHOSIS 



The child who observes a crawling caterpillar change into 

 a winged butterfly is enthralled by a mystery which seems one of 

 nature's greatest wonders. This is, however, only one of several 

 patterns of growth that we find among insects. It involves four 

 different forms. Butterflies, moths and others that grow this way 

 are said to have a "complete metamorphosis." (The word is from 

 the Greek and means "change of form.") 



The first form is the egg; the next is the larva. Then comes the 

 pupal stage, a period of relatively quiet resting. Finally the pupa 

 develops into the adult. The larva of a butterfly we commonly 

 call a caterpillar; the term for the pupa is "chrysalis." The larva 

 of a fly, you may know as a "maggot"; that of a bee or a beetle, 

 as a "grub." 



INCOMPLETE METAMORPHOSIS 



Another type of insect growth is called an "incomplete 

 metamorphosis" because the insects do not go through any strik- 

 ing change in form during their growth after the egg stage. They 

 do, however, gradually change their proportions. The young of 

 this group, known as "nymphs," are like adults in most respects. 

 They eat the same food and are much the same in appearance 

 and behavior. The grasshopper is a well-known member of this 

 group. 



In the case of some water-dwelling nymphs, such as the young 

 of the dragonfly, we see a great change when the gilled nymph 

 becomes an adult; but the metamorphosis is still considered 

 "incomplete." 



