LEPIDOPTERA. 203 



a native of China, but has been distributed to all of the 

 warm parts of the earth. Like other caterpillars, they form 

 their cocoons, and then these are heated to kill the pupa and 

 the silk of the cocoon is unwound, and after proper treat- 

 ment becomes the silk of commerce. We have several spe- 

 cies of silkworms in this country some of which make a 

 stronger silk than the Chinese species; but although a few 

 articles have been made from it, it has no economic impor- 

 tance. These large American silkworm-moths are known 

 as Polyphemus-, Promethea-, Cecropia- and lo moths, and 

 they, together with the beautiful green luna-moth, are great 

 favorites with collectors. 



The skippers are a group of small butterflies in which 

 the clubbed antennae are bent into a hook at the tip. They 

 are called skippers on account of their jerky flight. 



The swallowtails are well-known forms of butterflies in 

 which the hind wings are prolonged into tails, whence the 

 name. The larvae of these forms are usually brightly col- 

 ored, but they are protected by a pair of " stink-horns," 

 which they can project at will from the region of the neck, 

 and which give off, in most cases, a most offensive odor. 



Another group of butterflies, whitish-yellow or orange 

 in color, are typified by the cabbage-butterflies. We had 

 some of these which were bad enough ; but a few years ago 

 the European cabbage-butterfly came to this country and 

 became the greatest pest of all our butterflies. 



Of smaller size the most delicate of all our butterflies 

 are those forms which have received the common names 

 of the blues, the coppers, and the hair-streaks, from their 

 predominant colors and from the ornamentation of the 

 wings. 



Of larger size are the group of " four-legged" butterflies, 

 so called because the first pair of legs are so small as to be 



