FAMILY TYPICAL BUTTERFLIES. 143 



43. Genus Piekis. 



PIERIS OLERACEA— THE GRAY-VEINED WHITE. 



(Pontia oleracea, Pontia casta, Pieris napi, Pieris frigida, Pieris 



cruciferarum. ) 



Butterfly. — Wings white without markings, or with the veins 

 more or less broadly mapped beneath with gray, especially on the 

 hind wings and on the tips of the fore wings, and the same regions 

 washed with pale yellow. Expanse about 2 inches. 



Caterpillar. — Head green. Body slender, naked, pilose, green, 

 minutely dotted with black, except on a dorsal stripe which is not 

 otherwise distinguished. Length f inch. 



Chrysalis. — With compressed conical elevations above on the 

 middle of the thorax and on sides of second and third abdominal 

 segments, those of the third distinctly flaring, the frontal projec- 

 tion much longer than broad, the wing-cases not protruding be- 

 neath ; color green, the elevated portions infuscated. Length 

 fully f inch. 



This northern species occurs throughout all but the 

 southern parts of our region, though in scanty numbers 

 except in mountainous districts; it appears, however, to be 

 absent from the prairies west of the Mississippi, and 

 wherever it has come in contact with P. rajjae, it has be- 

 come relatively rare; it seems to be more commonly found 

 in open places in the vicinity of woods than about farms 

 (where P. rapae is most common) and is in every respect 

 more feral than the introduced pest. It is triple-brooded, 

 wintering in the chrysalis; the first brood appears at the 

 end of April or early in May, according to the season, and 

 flies somewhat into June; the second at the very end of 

 June or early in July and flies nearly to the end of the 

 latter month ; the third early in August or occasionally at 

 the end of July and disappears early in September. The 

 eggs, which are Florence-flask-shaped, tapering from the 

 middle upward and with about thirteen vertical ribs, are 

 pale greenish yellow, and are laid singly on the under sur- 

 face of leaves, often several on a leaf, and hatch in from five 



