ELEMENTARY STUDIES IN INSECT LIFE 



incomplete metamorphosis, and in the immature stages 

 are spoken of as nymphs. 



Complete Metamorphosis.-- It is sometimes difficult to 

 associate the identity of a bright-winged butterfly with 

 that of some ugly caterpillar. Nevertheless, every but- 

 terfly was once a caterpillar, and not infrequently the 

 most repulsive caterpillar becomes the most attractive 

 butterfly. The honey-bee conies from a white grub, the 

 house-fly from a maggot. Insects which develop in this 

 manner are said to have a complete metamorphosis. 

 They emerge from the egg in a worm-like form called 

 the larva, or the larval stage ; growing to considerable 

 size in this form, they pass into a very dissimilar stage, 

 the chrysalis or pupal stage, in which the insect is 

 quiescent and non-feeding, and during which the fully 

 matured insect is developed. 



Molting 1 . All insects, during their growth and de- 

 velopment from the egg to maturity, undergo at certain 

 periods a process commonly known as molting. The 

 outward indication of this process consists in the shed- 

 ding of the skin. These changes are not alone for the 

 discarding of unyielding or chitinous coverings to 

 permit enlargement in bodily size, but are as well 

 physiological processes, attended by marked changes 

 in tissues and organs. 



Insects with a complete metamorphosis appear in 

 four forms: the egg, the larva, the pupa, and the adult; 

 while in those with incomplete metamorphosis there are 

 but three forms : the egg, the nymph, and the adult. 

 In order that these two methods of insect growth and 

 development may be more fully understood, a type of 

 each has been selected for illustration. 



