Take steps to protect swallowtail butterfly population
Q. How can I support the swallowtail butterfly population? It's great to see the monarchs but I would like to have another variety in my yard.
A. Swallowtail butterflies are beautiful insects easily identified by their large size and hind wing tails that remind one of the forked tails of swallows.
Welcome these visitors to your garden as they are skilled pollinators for a number of plants including trees, shrubs and herbs. Often distasteful to birds, the adults feed on flower nectar whereas the larvae feed on vegetation. The caterpillar has yellow or red structures that extend from behind the head when threatened. The pupa are protectively colored and overwinters in this stage.
Swallowtails are found worldwide with over 550 species. Those common to the Chicago area include black swallowtail (Papilio polyxenes), tiger swallowtail (Papilio glaucus) and spicebush swallowtail (Papilio trollus). Less common to the area but still native to Illinois species include giant swallowtail (Papilio crestphontes), zebra swallowtail (Eurytides marcellus) and pipevine swallowtail (Battus philenor).
Most of the things you do to attract and sustain the monarch butterfly population will also benefit swallowtails. A good water source such as a pond or clean bird bath, nearby rocks for resting upon and tall grasses for shelter are all essential to survival. Most importantly, provide nectar plants for adults to feed upon and larval food for the young.
Each species has evolved around specific host plants. Carrot family plants such as dill, parsley and fennel will support the black swallowtail. Black cherry and tulip trees are host plants for the tiger swallowtail. Spicebush swallowtails favor spicebush and sassafras. Less common giant swallowtails seek out prickly ash and hoptree. Pawpaw trees are a must for zebra swallowtails. The pipevine swallowtail can be found where pipevine, Dutchman's pipe or related plants are established.
Nectar plants are shared across species. Illinois natives bee balm, cone flower, ironweed, Joe pye weed, butterfly weed and globe thistle are butterfly magnets. Try growing annuals such as zinnia and lantana. Lilac, buddleia and rose bushes also provide abundant nectar.
Avoid use of pesticides and inorganic fertilizer in your yard. When shopping for bedding plants, read the label carefully and avoid any plants that have been treated with neonicotinoids. Unfortunately, many big box stores carry bedding plants treated with this pesticide.
Finally, leave some vegetation standing in your garden for the winter. Unlike monarchs who famously migrate south for the winter months, swallowtails overwinter as chrysalis right here in Chicago. Too ambitious of a fall clean up will strip your yard of next year's brood. Leave some vegetation standing or piled in a corner of your yard all winter, and you will be the first in your neighborhood to welcome the butterflies back in the spring.
— Stephanie Kenny
• 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.