This past week, I've seen several Pipevine Swallowtail butterflies. Every year these lovely butterflies with their irridescent blue lower wings entertain us by visiting our butterfly garden in large numbers during the summer months. It got me to wondering though, where will they get nectar this time of the year, since there are still very few wildflowers blooming? Are the butterflies emerging too early, perhaps fooled by warming temperatures? What about their caterpillars? Will they be able to find food plants in early March? Join me to learn more, including some fascinating interactions of these butterflies with the plants their larvae feed on.
Pipevine Swallowtails are found from southern Minnesota, Michigan and central Connecticut, south to Florida and Texas. Their preferred habitat is forest edges, pinelands, and open dry woods, which describes our place in South Central Texas perfectly. We are located in the "Lost Pines", an isolated stand of oak-pine woodland that is the farthest western reach of the Loblolly pine forests that once stretched to East Texas, where I grew up.
Pipevine Swallowtail caterpillars feed exclusively on leaves of plants belonging to the genus Aristolochia. Aristolochia leaves contain a toxin, aristolochic acid, which makes the caterpillars unpalatable to predators. One Aristolochia found in our area is a kind of Dutchman's Pipe, which seems to like our sandy soil.
If the butterflies I've seen recently find mates, will there be food plants for the caterpillars? Sure enough, I spotted some of the pipevine plants emerging in the woods, just as the first Pipevine Swallowtail butterflies have started to emerge from their chrsallises.
Once I found a number of tiny, recently hatched Pipevine Swallowtail caterpillars on the underside of one of the heart-shaped leaves, which provided a perfect umbrella from spring rains.
Another interesting Aristolochia found in our area is called Swanflower. It is what is known as a grass mimic, apparently to fool the female Pipevine Swallowtail butterflies so that they don't lay their eggs on the plant, as the caterpillars will completely devour all of the leaves on a plant before moving on. We often see them hurrying along in our meadows, looking for their next meal. Swanflowers are difficult to spot, until they bloom. The first time I saw a flower of this plant, I thought it might be some kind of carnivorous plant. It really does resemble a swan!
A close-up view of the flower-
Pipevine Swallowtail caterpillars are not only protected by their unpalatability. David L. Wagner suggests in his fascinating field guide Caterpillars of North America, that they may be mimics of the velvet worm, making them even more unattractive to predators-
The caterpillar of the Pipevine Swallowtail is a most unlikely looking creature whose resemblance to a velvet worm ( onychophoran) may be more than accidental. Velvet worms hunt their prey in a bizarre if not somewhat disgusting fashion- by launching strings of slime from a gland in their head that entangles their victm.Not sure if we have velvet worms around here. David Attenborough shows us a velvet worm in action. Pipevine caterpillars do have projections from their bodies that look a lot like tentacles. This is the red form, but they can also be black. My granddaughter calls them "squishy spot caterpillars".
The butterflies I have seen would be just emerging from their chrysallis, possibly males patrolling in search of females.
Fortunately for these early butterflies, a few wildflowers have started to flower in the past few days- Verbenas, Wild Onions, Winter Vetch, and Dandelions. Here's one of the butterflies on Phlox towards the end of March of last year-
Later in the summer, they are constant visitors to the Lantana in our butterfly garden.
What butterflies and wildflowers are you starting to see in your area?
Updated by loblolly at Sun Mar 13, 2011, 06:20:11 PM
As of yesterday, more wildflowers are starting to bloom, including the first Bluebonnet.Updated by loblolly at Sun Mar 13, 2011, 11:05:45 PM
As the populations of pollinators decline, counts are important in helping determine the causes .The National Butterfly Association (www.naba.org) has Citizen Science butterfly counts Memorial Day and in July. They also have a feature called "Butterflies I Have Seen" which allows you to report sightings, and keep life lists of butterflies, as well as information on creating butterfly habitats.Updated by loblolly at Mon Mar 14, 2011, 09:58:22 AM
And finally, if you are interested in attracting Pipevine Swallowtails to your backyard, the National Butterfly Association has information on Aristolochia for different areas of the country. Learn more about NABA's Pipedream Project at www.nababutterfly.com/pipevine.html