Have you seen any Swallowtail butterflies in your garden yet this summer? Next to Monarch butterflies, Swallowtails are the largest butterflies you’ll see in the Great Lakes Bay Region. These colorful insects get their name from the extended “tails” on their hind wings that resemble the forked tails of swallows.
Four Swallowtail species—Eastern Tiger, Giant, Black, and Spicebush—live in the region from May through September, with two flight periods (generally May – June and August – September). After spending the winter in chrysalis form, the adults fly around on warm sunny days, seeking nectar for nourishment. Males patrol for females along forest edges and trails, and females send out a pheromone to attract potential mates. After mating, females search for specific host plants and lay eggs singly on the plant’s leaves. Butterflies “taste” plants, using the sensory cells on their feet to determine on what plants to lay eggs.
Common host plants for Eastern Tiger Swallowtails include Wild Black Cherry, Tulip, Ash, Cottonwood, and Basswood trees and Lilac bushes. Finding Eastern Tiger Swallowtail caterpillars is a challenge. The green mature caterpillars have two false eyespots on their swollen thorax and rest on the silken mat found within a curled leaf.
Eastern Tiger Swallowtails need 60 days to complete metamorphosis. Adults sip nectar from many field wildflowers, including Wild Bergamot, Joe-pye Weed, Common Milkweed, Blazing Star, and Ironweed. Males frequently “puddle,” whereby several butterflies will land on wet sand or mud to sip minerals that they need for reproduction.
Giant Swallowtails are Michigan’s largest butterfly species; they have a 6-inch wingspan. Their mottled brown and tan-colored caterpillars camouflage themselves as bird droppings on their host plants, Prickly Ash and Hop-Tree. Like all Swallowtail caterpillars, they react to predators or a human disturbance by pushing out their orange fleshy odor-producing “forks” from their head.
Spicebush Swallowtails prefer the understory tree leaves of Spicebush and Sassafras as their host plants. Black Swallowtails are the exception in this butterfly family; instead of trees, they choose dill, parsley, fennel, or carrot leaves, or Queen Anne’s Lace as host plants. You may see Black Swallowtails more frequently because they complete a life cycle in 28 to 42 days.
Swallowtails produce two or three broods per year, depending on available food supply and weather conditions. The last chrysalis overwinters. To attract these beautiful “flying flowers,” grow their host and nectar plants in your landscape!
How can you enjoy butterflies?
Learn. You can identify butterfly species by consulting field guides or websites or by attending nature center programs. Become familiar with species characteristics.
Plant. Wildflower gardens support biodiversity. To plant your own, choose a location that gets at least six hours of sunlight a day. Pick native plants that will bloom successively throughout the growing season. Butterflies prefer flat-topped flower clusters. Group at least three plants of each species and similar colors together, because butterfly eyes see waves of color.
Shop. When shopping for plants, refer to their scientific names because plants usually have more than one common name. The Michigan Native Plant Producers Association supplies native genotypes adapted to our region. Grow host plants for caterpillars and nectar plants for a variety of adults.
Care. Butterflies get moisture from shallow mud puddles or rotting fruit. Do not use pesticides.
Photograph. Warm, sunny days are best for photographing butterflies. Focus your camera on a spot where butterflies may land. Use a high shutter speed of 1/500 or more to minimize camera shake and stop the subject’s action. With a good-quality zoom lens, you can stay a respectful distance away and not scare off the butterfly. To take a sharp image, focus on the butterfly’s eyes and keep your body parallel to your camera lens.