Although butterflies have been with us all summer, fall seems to bring out some of the most spectacular – the swallowtails. Two that are particularly impressive are the Spicebush Swallowtail and the Black Swallowtail. With wingspreads up to 4 inches, these largely black, graceful insects drift lazily around seeking a mate, taking a sip of nectar here and there, and laying eggs. Other swallowtails have wings up to 6 inches across. Swallowtails get their name from the long, trailing tail on the lower edge of their hind wing that must have reminded early naturalists of the trailing edges of swallow’s tails.
After mating, adult females lay eggs on plants their larvae will enjoy eating after hatching. Spicebush swallowtail larvae eat spicebush - of course, sassafras, prickly ash, and tulip tree, among others. Black swallowtail young eat plants in the parsley family, including carrots and Queen-Anne’s-Lace, as well as celery and dill.
From the time of their hatching, the larvae eat constantly, growing larger each day. Then comes a time when they stop feasting, perch unmoving on a branch, and look sick. Actually, what they are doing is changing into a smooth, hard-shelled chrysalis containing their pupa. Moths, on the other hand, spin a web sleeping bag called a cocoon. The chrysalis remains unmoving for about 9-10 days (or all winter) as the pupa changes into a mature butterfly by a process called metamorphosis. Finally, the chrysalis splits and the mature butterfly drags itself laboriously out, its wings crumpled and useless. Perching in the sun, the butterfly pumps body fluids slowly into its wrinkled wings, gradually unfolding them. They soon dry and become strong enough for flight. Then, in the blink of an eye, the butterfly flits away.
Adult black swallowtails feed on the nectar of red clover, milkweed, and thistles as well as a wide variety of garden plants, while spicebush swallowtails drink flower nectar from honeysuckle, jewelweed, thistles, milkweed, azalea, dogbane, lantana, mimosa, and garden plants. So, if you want to attract these lovely creatures, plant their favorite foods. The National Wildlife Federation maintains a website loaded with suggestions on desirable plants and butterfly facts. Incidentally, butterflies taste with their feet to determine whether a plant is to their liking. But, don’t tell your little kids this or they’ll want to wade in their dinner plates.
Butterfly wings are covered with the Lepidoptera equivalent of feathers, although entomologists call them scales. Touching a butterfly’s wings leaves your fingers coated with “dust” the color of the wings – their scales.
The scales are responsible for giving butterflies their distinctive color patterns and may help them maintain their body temperature. They also help them escape from spider webs, since the scales easily slip off the wings, helping the butterfly get away, leaving only a smudge of color on the web. Handling butterflies removes large quantities of these scales and may shorten their already brief 10-14-day lifespan.
The colors and patterns on a butterfly’s wings probably help them identify mates, but organs in their abdomen emit chemical attractants called pheromones that drift on the breeze and allow suitors to follow their increasing concentration “upstream” to potential mates.
Coloration also warns predators to avoid certain butterflies. Monarch butterfly larvae feed on milkweed which contains poisonous chemicals. They don’t hurt the caterpillar, but they are passed on to the adult, and a bird scooping up a Monarch will soon become very sick and quickly learn to avoid them in the future. Viceroy butterflies use this information to their benefit. They look like Monarchs but are quite tasty and harmless. Nevertheless, birds with previous bad experiences with Monarchs avoid these look-alikes.
Tiger Swallowtails have a slightly darker but similarly patterned relative called the Pipevine Swallowtail that is poisonous, and the Tiger Swallowtails benefit from this.
Butterflies are magical creatures that some have dubbed “flowers of the sky.” Indeed, they are by far, the most eye-catching animals you’re likely to see on a casual stroll through fields and forests. Most people are fascinated by them. Butterfly houses and gardens open to the public are found throughout the United States, and a list of many of them can be found on the web at butterflywebsite.com. Recently I spent several hours in a large one in Florida at the Key West Butterfly and Nature Conservancy. Moody Gardens in Galveston has a huge glassed-in tropical rainforest pyramid through which visitors can stroll amid exotic plants, birds, and butterflies. Austin, San Antonio, Houston, and Ft. Worth also have walk-in butterfly houses or gardens. The effect of hundreds of these insect jewels flitting all around you and even perching on your shoulder or head has to be experienced. It’s truly magical. Try it. You’ll like it.
Dr. Risk is a professor emeritus in the College of Forestry and Agriculture at Stephen F. Austin State University in Nacogdoches, Texas. Content © Paul H. Risk, Ph.D. All rights reserved, except where otherwise noted. Click firstname.lastname@example.org to send questions, comments, or request permission for use.