LEPIDOP TERA . 357 



pupa is represented by Figure 436 and the cocoon by Figure 



437. 



The Cecropia-moth occurs from the Atlantic coast to the 

 Rocky Mountains. In the far West its place is taken by 

 very closely allied forms, which are supposed to be distinct. 

 In these the ground-color of the wings is usually a reddish 

 or dusky brown. The form occurring in Utah and Arizona 

 is Samia gloveri (S. glov'er-i) ; that found on the Pacific 

 coast is Samia californica. 



The Ailanth US-worm, Philosamia cynthia (Phil-o-sa'mi-a 

 cyn'thi-a), is an Asiatic species that has been introduced into 

 this country. It has become a pest in the vicinity of New York, 

 where it infests the Ailanthus shade-trees. The moth differs 

 from all our native species of this family in having rows of 

 tufts of white hairs on the abdomen. The cocoon resembles 

 that of the Promethea-moth. 



Family Lacosomid^ (Lac-o-som'i-dae). 

 The Sack-bearing Frenulum- losers. 



This family so far as is now known includes only two 

 species that are found in the United States, and both of 

 these are rare ; farther south several other species occur. 

 They are our only native Frenulum-losers that retain a rudi- 

 ment of the frenulum, but, as in the silk-worm, this frenulum 

 is very small and the humeral angle is greatly expanded, so 

 it is probable that the frenulum is of but little if any use 

 (Fig. 438). It was the presence of this rudiment that first 

 suggested to the writer that those families of the Lepidop- 

 tera that we have termed Frenulum-losers were descended 

 from frenulum-bearing ancestors. 



The Lacosomidse seem to be the sole survivors of a very 

 distinct Hne of descent. In many respects they appear to 

 be closely allied to the Saturniina, especially to the Bom- 

 bycidae. But they differ markedly both in the structure and 

 in the habits of the larvae ; and, too, the wings of the adult, 



