Kansas State University


Extension Entomology

Tag: mature caterpillars

Parsleyworm Or Black Swallowtail Caterpillars

by–Dr. Raymond Cloyd

This is the time of year we start getting inquiries regarding the parsleyworm or black swallowtail (Papilio polyxenes) caterpillars. The caterpillars primarily feed on the leaves of dill, fennel, and parsley although they will sometimes feed on plants such as Queen Anne’s lace, celery, and similar plants in the carrot family (Apiaceae or Umbelliferae). Young caterpillars are mottled black and white, which results in them resembling bird droppings. Mature caterpillars possess bands of green, yellow, white, and black. Furthermore, there are six yellow spots within each black band. Full-grown caterpillars can be up to 2.0 inches in length.

newFigure1Parsleyworm Caterpillar

Figure 1: Parsleyworm — October 2015

Parsleyworm overwinters as a pupa or chrysalis attached to the bark of trees, sides of buildings, or other protected habitats. Adults typically emerge in May and June, and mated females deposit eggs on plants in the Apiaceae or Umbelliferae family; laying several eggs per location. After eggs hatch, caterpillars feed for 3 to 4 weeks during which time they undergo a series of color changes as they mature. Full-grown caterpillars eventually move off plants to find a place to pupate. The caterpillars form gray pupae, which blend in with the surrounding background. After about two weeks, adults emerge from the pupa or chrysalis.

newFigure2Parsleywom Caterpillar


Figure 2: Parsleyworm Caterpillar

Adults are large black swallowtail butterflies with a wingspan of 2.0 to 3.5 inches. They are shiny black in color, occasionally with iridescent blue; and yellow bands or spots along the edge of the forewings and hindwings. The adults feed on the nectar of many different flower types. Females and males mate, and then females lay eggs that will result in the occurrence of the second generation sometime in August. There are usually two generations per year.