Egg - Spherical and about 1 mm in diameter, the egg gradually changes from pale yellow to reddish-brown.
Larva - When fully grown, the parsleyworm is about 40 mm long. Its yellowish-green body has transverse black bands and deep yellow or orange spots on these black areas. Behind the yellowish-green, black-striped head is a pair of yellow or red scent organs which protrude like horns when the caterpillar is disturbed. Early instar larvae resemble mature larvae in coloration but may have spines.
Pupa - Known as a chrysalis, the sharply angled pupa is dull gray and mottled with black and brown. It is about 32 mm long.
Host Plants - Parsleyworms feed primarily on celery, parsley, carrot, parsnip, dill, and other closely related herbs and weeds.
Damage - Though foliage feeders, parsleyworms are not usually serious pests. They usually eat leaves, but occasionally attack blossoms and underdeveloped seeds. Often noticed, even in low numbers because of their striking and sometimes formidable appearance, these caterpillars do little damage to plants and do not sting or attack man.
Life History - Parsleyworms overwinter as pupae, or chrysalides, attached to stems or fallen leaves. Black swallowtail butterflies emerge in April or early May. Soon afterwards, eggs are deposited on plant foliage. Four to 9 days later, eggs hatch and the young larvae begin feeding on leaves. The period of larval development varies with geographic location but rarely lasts longer than 4 weeks. Mature larvae become chrysalides and are attached to host plants by silken threads about their middles. Butterflies emerge from these non-overwintering pupae in 9 to 15 days. The number of annual generations varies from two in northern states to three in St. Louis, Missouri, to four in the Gulf States. There are probably three generations per year in North Carolina.
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