THE LEPIDOPTERA 



283 



Family Saturniidae (The Giant Silkworms). In this family belong most of 

 the common, very large moths found in North America. Though their size 

 and that of their caterpillars attracts attention, these insects are of little economic 

 importance as the number of eggs laid by an individual is not very large and 

 they are generally well scattered so that few larvae are often found on any one 

 tree. If the silk of their cocoons could be utilized they would become industrially 

 important, but the thread is frequently broken so that reeling it is difficult and 

 expensive. 



One of the more common species in this family is the Cecropia Moth (Samia 

 cecropia L.), a very large, brownish-gray insect (Fig. 295) with a whitish, crescent- 

 shaped spot partly shaded with brown, near the center of each wing. Outside 

 this spot a whitish line crosses the wing and the outer margin is more or less 

 broken by black spots on a whitish ground. The abdomen is brown with white 

 crossbands. The caterpillar (See Fig. 21), which when full-grown is from three 



FIG. 297. Male Promethea Moth (Callosamia promethea Dru.), about two-thirds natural 



size. (Original.) 



to four inches long, is green with tubercles along its back, two pairs near the 

 head being coral red and the others yellow except the first and last pair which are 

 blue. The insect feeds on many kinds of plants, including some fruit and shade- 

 trees. The moths appear in late spring, the larvae feed during the summer, and 

 in the fall spin rather dense cocoons on the twigs of the trees, in which they 

 pupate and pass the winter 



A rather similar moth, though usually a little smaller, is the Polyphemus 

 Moth (Telea polyphemus Cram.), with brown wings crossed near the outer 

 margin by a blackish band (Fig. 296). The front wing has a transparent "eye" 

 spot with a yellow margin, around which is a black line. The hind wing has a 

 somewhat similar spot, but the black around it covers quite an area, particularly 

 toward the base of -the wing. The caterpillar is green with a yellow, oblique 

 line on the side of most of the segments of the abdomen and it feeds on many 

 fruit and forest trees. The cocoon is spun among leaves on the ground. 



Somewhat smaller, spreading about four inches, is the Promethea Moth (Call- 

 osamia promethea Dru.). The male moth (Fig. 297) is dark brown except toward 



