494 NATURAL HISTORY OF ARTHROPODS. 



at the extremity. Imago with the abdominal edge of the secondaries without a con- 

 cavity. Discoidal cellule closed. Hooks of the tarsi unindentate." 



Colias is one of the most widely spread genera, though for the most part confined 

 to the northern hemisphere, only a very few species being found south of the equator. 

 The great resemblance which many of the forms bear to each other has occasioned a 

 good deal of discussion as to their relative specific value, and Colias may be regarded 

 as a bone of contention among naturalists, though nothing but breeding from the egg 

 through successive generations will settle many of the points in dispute. Like many 

 of the following genera, the colors are shades of yellow with black borders and spots, 

 and the caterpillars are green, feeding on Trifolium, Astragalus, Melilotus, and kin- 

 dred plants. The most common species in the 

 United States is C. philodice, which is familiar 

 to every schoolboy throughout the country. It 

 passes into other forms as we go west, and many 

 entomologists are to be found who think that C. 

 eriphyle, C. Christina, and C. occidentalis, are but 

 local varieties of the common species. . Like Cal- 

 lidruas, species of Colias have been met at great 



FIG. 619. Colias philodice. J 



distance from land, and Mr. Darwin gives an in- 

 teresting account of one of these flights, observed by him : " One evening, when we 

 were about ten miles from the Bay of San Bias, vast numbers of butterflies in bands 

 or flocks of countless myriads, extended as far as the eye could range. Even by the 

 aid of a telescope it was not possible to see a space free from butterflies. The seamen 

 cried out ' it was snowing butterflies,' and such in fact was the appearance. More 

 species than one were present, but the main part belonged to a kind very similar to, 

 but not identical with, the common English Colias edusa. The species was probably 

 C. lesbia." 



Meganostoma^ which by some authors js united to the last genus, contains one of 

 the most beautiful insects of the whole sub-family. This is M. eiirydice, which has the 

 wings bright orange with a black border, over the whole surface being spread a bril- 

 liant purple sheen. The female is pale yellow, with little of the beauty of her partner. 

 The species is a native of California, where the caterpillar feeds upon a papilionaceous 

 plant of the genus Amorpha. Gonepteryx is a grand genus of few species, in which 

 the wings are falcate at their apex, the veins swollen and distinctly thickened, espe- 

 cially at their base, while the lower side of the wings is wrinkled like a leaf. Two very 

 large species are natives of Mexico, viz., G. dorinde and G. moerula. The former 

 white, with a large orange patch; the latter bright citron, with a very conspicuous 

 black discal dot. G. rhamni is a well-known European species, while the more beauti- 

 ful G. cleopatra extends into Africa and Asia Minor. 



The genus Catopsilia (=Callidryas) contains a number of very showy insects, 

 mostly of various shades of yellow. It occurs in the Old and New World, not a 

 few being found in India and Australia, while North and South America boasts of at 

 least twenty-five species. The most showy of these is C. philea, in which the wings 

 are of a bright golden yellow, with a large deep orange patch upon the costa. It is a 

 large insect, four to five inches across the wings, and frequently occurs in great quan- 

 tities from Mexico to Brazil. They often congregate in large numbers, and Mr. Bates 

 speaks of seeing so many at rest with the wings erect on the shoal of a muddy river, 

 that, " as they swayed about in the wind, they looked like a large bed of crocuses in 



