Butterflies offer lesson in metamorphosis to Warren residents
Published 12:00 am Sunday, August 30, 2009
It’s all in the metamorphosis — you know, the biological process by which some insects change drastically in structure.
With some insects, metamorphosis even involves changes in habits or behavior. For Fran Bunch and Amy Burr, the change in the insects they encountered was from just plain ugly to wonderfully, exotic-looking.
Bunch, a local homeowner, and Burr, a Warren County Master Gardener intern, almost simultaneously discovered large, scary-looking caterpillar larvae on their citrus trees. Bunch reported her sighting via a telephone call to the Extension office, but Burr used the “get-a-sample-into-a-jelly-jar-and-deliver-them-to-the-Extension-office” technique.
Upon inspection, it turns out the hideous caterpillars were larvae of giant swallowtail butterflies. The giant swallowtail, Papilio cresphontes, is a welcome visitor to butterfly gardens and general landscape plantings. The larvae or caterpillar stage, however, can be a pest due to its habit of feeding on the foliage of most citrus trees. Burr’s tree — a small, container-grown tangelo — certainly could not have withstood much leaf feeding. Lucky for the little tangelo, Burr’s observant eye spotted the “orangedogs,” as the larvae are called, as they would have completely defoliated her tree in short order.
One would probably just tolerate the critters on larger citrus trees in order to enjoy the soon-to-develop magnificent butterfly stage.
Adult giant swallowtails are large butterflies with a forewing span of nearly 3 inches for males and a span of 2.5 for females. The dorsal wing surfaces of the butterfly are black with a striking diagonal yellow bar across the forewings. The ventral wing surfaces are primarily yellow. The five larval instars differ in appearance but they all share a resemblance to bird droppings. The younger instars are predominantly black with a white saddle while the older instars are mottled dark brown with a posterior that is white or cream colored. It has been suggested that the older instars resemble small snakes. I am not sure if it was Bunch or Burr, but one of the ladies did describe the larvae as snake-worms.
Host plants of the larvae include members of the citrus family and several other tree species including mock orange trees, which are common along older fence rows. Adult butterflies sip nectar from many flowers. Sources include azalea, bougainvillea, Japanese honeysuckle, goldenrod, dame’s rocket, bouncing Bet and swamp milkweed. They may also sip liquid from manure. Adult males patrol flyways through pine woods or citrus groves searching for females. Flight is very strong and leisurely, and the butterflies may glide long distances between wing beats.
I got the impression that Burr did not necessarily welcome the snake-worms in her landscape, as she followed the advice of her Edna Drive neighbor who, according to Burr “recommends a good dusting of Sevin for about anything buggy.” There does happen to be an organic product — spinosad — on the market, which is effective on caterpillars, but safe for adult butterflies and other insect predators.
John C. Coccaro is county Extension director. Write to him at 1100-C Grove St., Vicksburg, MS 39180 or call 601-636-5442. E-mail him at jcoccaro@ext.msstate.edu