PAPILIONID^. 323 



The genus Pieris contains a laige nnmber of white butterflies of 

 medium size, many of wliich are adorned with spots or markings of 

 dark Ijrown. Beneath, they are frequently yelhnvish white in color. 

 The caterpillars are generall}- green, and feed on cruciferous plants, 

 some of the species doing considerable damage. 



The chrysalis is somewhat angular, usually light in color, and 

 although naked and fi'agile, 'and usually exposed to ever}^ breeze 

 that blows, it is capable of withstanding the severe frosts and storms 

 of winter, and rides safely anchoi'ed by its silken thread's. The in- 

 sects inhabit chiefly the northern hemisphere of both the old and the 

 new world. 



Our most abundant species is Pieris rapoi. This insect is a 

 European importation which has driven our native white Pieris 

 oleracea almost out of existence. It is one of the most plentiful of 

 butterflies, making its appearance earl}^ in the spring, and being two 

 or even three-brooded in some localities. It has a wide distribution 

 over our countr}- and Europe. The larva of this butteifly is a great 

 enemy to the market gardener and farmer, sometimes devouring liis 

 young cabbages and cauliflowers to such an extent that nothing but 

 the bare stalks remain standing in the field. 



The larva is green and covered with short down or fine hairs. 

 The chrysalis is grayish or sometimes light green. This insect has 

 gradually spread over the entire continent, and may be seen flying 

 in swarms over fields of cabbages or turnips anywhere from Maine 

 to Texas, New York to California, and no field of cruciferous plants 

 is safe from its attacks. 



The heads of the cabbages are often riddled and rendered worth- 

 less by the holes made by the larva?, and to destroy them is not an 

 easy matter. Catching the butterflies with a net when first they 

 make their appearance and before they can lay their eggs on the 

 young plants, is perhaps the best method of keeping their numbers 

 down. The vigorous use of the net for an hour a day for two or 

 three days at the right time, will so reduce the numbers of this 

 pest that the plants will get a good start. This is preferable to 

 using emulsions of any sort to kill the caterpillars, as they are apt to 

 make the plants unfit for food, a matter of considerable importance 

 to the agriculturist. 



Pieris oleracea^ a butterfly which not long ago was plentiful over 

 a large part of the north-eastein United States, presumably owing to 

 the introduction of Pieris rapce^ has now become very scarce except 



