THE LEPIDOPTERA 



293 



to avoid destruction. How such a change could be rapidly developed, 

 however, to such a degree as to enable its possessors to benefit by it, 

 has not been satisfactorily explained, and if it were not so developed 

 the individuals in which the change began could hardly differ enough 

 from their former condition to escape. Here remains one of the unsolved 

 problems of insect life. 



Family Satyridae (The Satyrs). — The insects belonging in this family are of 

 medium size, and nearly all have gray or brown wings with spots more or less 

 resembling eye spots (Fig. 312). They are common near the edges of woods and 

 sometimes drift out into the fields. One species is found only on the tops of the 

 White Mountains in New Hampshire and on the higher Rocky Mountains. 

 How these colonies became so widely separated is a question, though explanations 

 for it have been suggested. 



Fig. 312. — Satyr Butterfly {Cercyonis alope Fab.), natural size. {Original.) 



Family Pieridae. — In this family belong the medium sized or small 

 yellow butterflies of various shades and the white ones, common in all 

 parts of the country. About 50 kinds occur in the United States and 

 some of them are occasionally, and others almost always, injuriously 

 abundant in one place or another. 



The Imported Cabbage Butterfly {Pontia rapce L.). — This insect, a 

 native of Europe, appears to have reached Quebec about 1859. It spread 

 rapidly and ten years later had reached Massachusetts. Other specimens 

 arriving at New York and Charleston, N. C, also established centers 

 from which the insect spread in all directions, and it is now found nearly 

 everywhere in the United States. 



The adult (Fig. 313a) spreads a little less than two inches. Its wings 

 are white, the tip of the front wing grayish. In the male there is a black 

 spot near the center of the front wing and one on the front margin of 

 the hind wing, while in the female the front wing has a second black 

 spot behind the other. 



