Parsley partners with beautiful black swallowtail caterpillar

Q. Oh, my! What are those striped caterpillars doing on my parsley plant?

A. Lucky you!

Your parsley is playing host to the larval stage of one of our most beautiful and admired butterflies, the Eastern Black Swallowtail. The caterpillar can be recognized by its green bands alternating with yellow-dotted black bands which form a regular striped pattern going from side to side across its body. Unlike the caterpillar, the butterfly, whether male or female, is primarily black with markings of yellow, orange, powdery blue, and cream with a red dot on its hind wings.

A frequent visitor to open wet areas and gardens, the black swallowtail's host plants are primarily in the Apiaceae family, which includes carrot, wild parsnip, caraway, celery, dill, parsley, sweet fennel, and Queen Anne's lace. Butterflies are important pollinators, although their method of pollination is unlike that of bees. They taste with their feet, and typically favor the flat, clustered flowers that provide a "landing pad" as they probe for nectar, their preferred food and energy source. Thus, your parsley is a prime candidate!

Because females lay single eggs on host plants, usually on the new foliage and occasionally on flowers, there is usually little disturbance to these cultivated plants. Depending on temperature, the egg stage lasts 4-9 days, the larval (caterpillar) stage 10-30 days, and the pupal stage 18 days. With two broods per year, the first of the adult butterflies can be seen in mid-May until late June and the second from early July to late August. You can expect to see swallowtail butterflies during and after these two periods.

In the unlikely event you find there is an overabundance of caterpillars, they can be handpicked and shared with the neighborhood kids to grow their own swallowtails or plant more dill and parsley to accommodate all those caterpillars! Otherwise, enjoy the presence of this colorful Lepidoptera, whether in its youthful striped caterpillar stage or in its adult form -- as a mature, fluttering butterfly in your garden.

For further information, see the following sources:

www.fs.fed.us/wildflowers/pollinators/animals/butterflies.shtml

http://entnemdept.ufl.edu/creatures/bfly/bfly2/eastern_black_swallowtail.htm

­- Arlene Swartzman

Correction: Last week several farms were listed as having "you-pick" strawberries available. However, strawberry season is over for the year. Some of the farms listed last week will have other berries for picking, but please call ahead to verify availability.

• Provided by Master Gardeners through the Master Gardener Answer Desk, Friendship Park Conservatory, Des Plaines, and University of Illinois Extension, North Cook Branch Office, Arlington Heights. Call (847) 298-3502 on Wednesdays or email northcookmg@gmail.com. Visit web.extension.illinois.edu/mg.