ODD CATElirJLLARS. 1397 



This is a purely Aincricau geinis, ti)k'ral)ly well siipplieil with species, 

 iiiul aj)parciitly contiiieil mostly to the iiortheni tropics, with the exception 

 of the single species descrihed below, and which extends, east of the 

 Kocky Mountains, as tar north as the St. Lawrence. 



The butterrties of this genus are among the largest of Hcspcridae, and 

 have the anal anjrle of the hind wini^s proloniicd into an obtuse rounded 

 lobe, instead of the tails of tiie ])revious genus. The wings are very dark 

 brown, and the front pair furnished with yellow, vitreous, irregular markings, 

 mostly arranged in a transverse baud crossing the wing from the middle 

 of the costal margin toward, and nearly to, the anal angle ; there are also 

 a few very small spots in a transverse series near tlie apex ; the hind 

 wings arc devoid of markings above, but beneath are provided with a 

 very large spot of irregular shape, often pure silvery white, generally 

 having more or less the form of a broken band, crossing the middle of 

 the wing transversely. 



The history of our own species alone is known ; in the north this is 

 single brooded, wintering as a chrysalis, and flying in June and July. The 

 butterflies frequent open spots, are exceedingly vigorous, and have an 

 astonishingly rapid flight, vieing with that of the hawk moths. All the 

 wings are raised in repose. The eggs are laid singly, and the caterpillars, 

 which feed on Leguminosae, and sometimes injure locust trees by their 

 ravages, live singly and sluggishly, in nests formed of leaves connected by 

 bands of silk. The chrysalids are suspended at both extremities in 

 cocoons either made from the leaves of the tree, or upon or near the 

 ground of any chance substance. 



The e<r2's are vaulted and furnished with a moderate number of lonsfi- 

 tudinal ribs, extending their whole length. The caterpillars are plump 

 and cylindrical, or a little depressed, tapering toward either extremity, 

 with a strongly constricted neck and a very large head ; they are green, 

 ornamented with transverse stripes of yellow or green. The chrysalids 

 are dusky, stout and well rounded, but otherwise possess slight distinctive 

 characters, though they have an unusually subdued prothoracic Sjiiracle. 



EXCURSUS LIV.— ODD CATERPILLARS. 



Full of strange shapes, of habits, ami of forms, 

 Varying in subjects. 



Shakespeare.— ioce's Labour^s Lost. 

 Let's talk of graves, of worms ami epitaphs. 



Shakespeare.— Kiny Richard II. 



Caterpillars of Pieris rapae are green, cylindrical worms, and it is a 

 not uncommon supposition among the uninformed that such is the case 

 witli all caterpillars, except that they may differ in being hairy or spiny. 



