INSECTS INJURIOUS TO MISCELLANEOUS CROPS 367 



of yellow spots. On the inner angle of the hind-wing is a well- 

 marked eyespot, and the hind-wing terminates in a distinct 

 "tail." The female is somewhat larger, the inner row of yellow 

 spots is wanting, and the hind-wings are covered with pale-blue 

 scales on the posterior half. There is considerable variation, 

 however, in the color of both sexes. 



Life History. In the North the winter is passed in the chrys- 

 alis stage and the butterflies appear in May in New England, 

 while in the far South the butterflies hibernate over winter and 

 appear in March or April. The eggs are laid on the foliage and 

 are of a globular form, about one-twenty-fifth inch in diameter, 

 at first pale honey-yellow, but later reddish-brown. The eggs 

 hatch in from four to nine days. The young larvae are quite 

 dissimilar from the older stages, being nearly black with a white 

 band around the middle of the body (Fig. 309e). The larvae 

 feed exclusively on umbelliferous plants, including besides those 

 mentioned, caraway, fennel, parsnip, dill, wild carrot, wild pars- 

 nip, and other weeds of this family. The full-grown larva is 

 shown, natural size, in Fig. 309, a. It is bright green, sometimes 

 yellowish, and marked with rings and spots of velvety black as 

 illustrated. Just back of the prothorax is a pair of membranous 

 yellow horns called osrnateria, which give off a peculiar pungent 

 odor, which is quite disagreeable and evidently aids in frighten- 

 ing away enemies. These osrnateria are soft, retractile organs, 

 which are drawn back between the segments and are extruded 

 only when the larva is disturbed. 



In the far South the larva will become grown in ten days, 

 but in the North it requires three to four weeks. The cater- 

 pillar then attaches itself to some part of the plant by the anal 

 prolegs, and fastens a strong loop of silk around the thorax, and 

 sheds its skin, leaving the chrysalis or pupa firmly attached to 

 the leaf or stem as shown in Fig. 309, /. The chrysalis is a dull 

 gray color marked with black and brown and about 1% inches 

 long. In from ten days to two weeks the butterfly emerges 

 from the chrysalis. Thus the complete life cycle may be passed 

 in twenty-two days in the South to eight weeks in the North. 

 In the North there are but two generations a year, while in the 

 South there are probably three or four. 



Control. The caterpillars are so readily seen, and if not seen 

 they soon reveal their presence by the peculiar odor when dis- 



