By Whitney Cranshaw, Colorado State University Cooperative Extension specialist, entomology
The parsleyworm is one of the most striking insects in the garden. These bright-colored caterpillars have a fancy for parsley, dill and the occasional carrot. When disturbed, they project a pair of fleshy, smelly "horns," designed to scare away predators.
Parsleyworms are fairly easy to control, if you want to do that. They are conspicuous and are easily hand-picked. The caterpillars also are susceptible to insecticides, such as Sevin or Bacillus thuringiensis, and are naturally attacked by parasites.
You should, however, consider leaving this insect pest alone -- or even encouraging it. These caterpillars transform into the black swallowtail butterfly, a large, attractive insect that will visit flowers and suck nectar. The possibility of enjoying a few more black swallowtails in the yard often makes it worthwhile to plant a little extra parsley or dill to feed the caterpillars.
Photograph courtesy of Lynne Conroy.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010