Some of nature’s most enchanting creatures are making their fall appearance in the Lowcountry these days.
Those who find butterflies intriguing have got quite a bit to see.
Of the three butterfly flight periods each year, usually early to late spring, late spring to early summer and late summer to early fall, the latter is the most active, experts say.
No doubt, butterflies are busy feeding, reproducing and pollinating flowers. Yet experts say it’s almost impossible to figure whether they are out in greater or fewer numbers this fall than the last one.
Regardless, it’s a great time for butterfly gardeners such as Jock Stender of West Ashley, who is sowing seeds to ensure that the plants his favorite butterflies need will be there.
Stender plants for butterflies such as the Gulf and variegated fritillary, zebra longwings, monarchs, cloudless sulphurs and, of course, the Eastern tiger swallowtail, South Carolina’s state butterfly.
As butterflies travel among plants for nectar, their flight fuel, they carry the pollen that flowers need to grow, say Billy McCord, S.C. Department of Natural Resources wildlife biologist.
During the process, female butterflies lay eggs, he says. Those eggs hatch as caterpillars in little more than a week. Caterpillars feed on the plants as they grow. After shedding their skins up to five times, the insect progresses through the pupa stage. It emerges as a butterfly in about two weeks.
Stender plants not only because he likes to see the butterflies in his yard but to help compensate for the loss of butterfly habitat to roads, shopping centers and residences.
In many parts of the Lowcountry, Gulf fritillary and cloudless sulphur butterfly populations are booming, Brian Scholtens says. The major reason is weather, which almost always accounts for ups and downs among an area’s common species, he says.
“This year, I have seen more Gulf fritillaries and cloudless sulphurs probably than ever before,” Scholtens says.
“Those are only our two most common species. We have more than 100 species of butterflies. Some will never do as well as they once did because we’ve destroyed most of their habit.”
There have been two consecutive mild winters in a row, and most butterflies were not negatively affected, he says.
Three years ago, there was a fairly cold winter and a drop in population the next year.
The other major effect on butterfly populations is rain, Scholtens says. On the coast, there has been plenty of rain, and host plants are growing very well and supporting lots of the more common species.
Gulf fritillaries eat only passion flower, also called maypop, a common weedy vine planted in many gardens because it has pretty purple flower, Scholtens says.
The cloudless sulphur eats a relative of the pea plant called cassia, a bright yellow roadside weed, and some other plants.
Most butterflies prefer forest and marsh areas such as the Francis Marion National Forest, Scholtens says. Some live only in such areas. So those are not found in backyard habitats such as those encouraged by many environmental groups, which attract only a handful of those commonly seen.
While there might be plenty of Gulf fritillaries and cloudless sulfurs around the Lowcountry, other butterflies have low numbers or are missing altogether, says Dwight Williams, director of Cypress Gardens, which has a butterfly house.
“We do surveys periodically here at Cypress Gardens,” says Williams, an entomologist. “A lot of species that should be coming here are not coming.”
In some areas, such as McClellanville, low numbers may be the result of mosquito spraying, he says. But that does not explain low numbers at Cypress Gardens because no such spraying occurs there.
Dennis Forsythe, biology professor emeritus at The Citadel, has been surveying the distribution of butterflies across South Carolina for more than a decade and has noticed some trends in the Lowcountry.
There has been a major surge in the pipe vine swallowtail in the Lowcountry this year, Forsythe says. On the coast, the host plant is the Virginia snake root.
Forsythe says he had not seen a painted lady anywhere in the state for about three years, but he recently saw several in his James Island yard. They have several host plants, including thistles and marrows.
The story, however does not appear to be as fortunate for the palamedes swallowtail, Forsythe says. The species may be declining because its only host plant, red bay, has laurel wilt disease, spread by the ambrosia beetle that believed to have come in from China through Savannah.
“Right now, the butterflies are using the leaves of red bay sprouts (to lay their eggs), Forsythe says. This is the third year that the wilt has been affecting the red bay, he says. The impact on the butterfly species is uncertain.
It’s difficult to determine the status of butterflies because many factors, including rainfall, influence their development, says DNR’s McCord. When there is normal rainfall, they usually increase dramatically from one generation to the next. The reverse usually is true when there has been a severe drought.
The problem with one-day counts that take place once a year is that butterflies have a short life expectancy, usually two to three weeks, he says. Typically, the highest populations are from late September to early October. But the time that populations peak varies from year to year.
You would need to conduct numerous counts throughout a season.
McCord says he is unaware of anyone doing long-term site-specific studies of the more than 100 species usually seen in the Lowcountry.
Locally, residents may be seeing monarch butterflies, whose population will peak along the coast from mid- to late October, says McCord, who has tagged them for the Monarch Watch project for 17 years.
Hardly any Monarchs tagged on the East Coast have ever been recovered in Mexico, where millions congregate during the winter, he says.
Ones tagged here have been found in Cuba and South Florida, and some of them winter between Wilmington, N.C., and Savannah.
The biggest impact on butterfly numbers is that the increased development for humans has eliminated or downgraded the habitat they and other insects need to survive.
In addition, McCord says that since most butterfly populations occur over a wide area, they are mobile and may recolonize if a habitat that has been destroyed rebounds.
For example, a species called the king’s hairstreak, common in the Long Point Road area 30 years ago, is no longer seen. The species, which has a 1-inch wingspan, is dependent on a plant called horse sugar during its caterpillar stage.
While the host plant is widely distributed, the small King’s hairstreak does not fly far, McCord says. Even if the species’ habitat in Mount Pleasant were to rebound, there would be little chance that others of the species could travel to that Mount Pleasant habitat and repopulate it.
“While you can plant a backyard wildlife habitat, you can’t put the entire natural diversity there,” McCord says. “Knowing which plants support certain butterfly species is not enough.”
Reach Wevonneda Minis at 937-5705.