The zebra swallowtail can be confused with no other butterfly in our area. Its pale greenish-white triangular wings are zebra-striped with black and accented with blue and brilliant red. It has extremely long tails, and flies in a curious "bat-like" fashion. Originally grouped with the other swallowtails in the genus Papilio, it was later renamed Graphium marcellus, a name still encountered occasionally in older books. Today it is known by the Latin name Eurytides marcellus.
Zebra swallowtails in our area begin to emerge from their overwintering pupae as early as late March, but become most common in late April through May. There are usually two broods, with the early spring individuals being markedly smaller and having shorter tails than the later forms. Most reports are that the female deposits her pale green, spherical eggs singly on the lower leaves of young pawpaw trees, but at Mason Neck Regional Park in Fairfax County, Virginia I have observed that many of the early spring females prefer to oviposit on the trunks of small saplings, usually within 12"-18" from the ground. A single small sapling can be observed to have several ova on it, and although I never found any young larvae, I have seen cases where many of the ova have already hatched. The larvae are most active at night, so in this instance they may have been hiding near the base of the plant during the daytime.
Males patrol the understory for females, normally flying 3´ to 6´ above the ground. Males may also be found "puddling."
John and Gloria Tveten report that the larvae are quite cannibalistic. They also report that, while the larvae are usually described as pale green, they have observed a brown variety in their studies in Texas. I have also located the brown caterpillars at Mason Neck. It has been well reported that the pupae may be either green or brown, but there appears to be no correlation between caterpillar color and pupa color. Pupation usually occurs under the leaves, and the pupae hibernate.
Adult zebra swallowtails nectar at flowers, and Paul Opler notes that the early spring individuals in our area seem to subsist mainly on blueberries, redbud, blackberry, and lilac. The later forms, he says, use common milkweed, dogbane, and vipers bugloss. They may also be seen nectaring at butterfly bush.
If you´ve not had a chance to observe this butterfly firsthand, it would be well worth seeking it out. They are quite common all along the Potomac in low woods wherever pawpaw is growing, and their habit makes it fairly easy to observe them.
Bibliography:
Brown, Melvin L. And Russel G. Brown (1972), The Woody Plants of Maryland, Port City Press, Baltimore, Maryland.
Opler, Paul and George O. Krizek, (1984), Butterflies East of the Great Plains, The Johns Hopkins University Press, Baltimore and London.
Scott, James A. (1986), The Butterflies of North America: A Natural History and Field Guide, Stanford University Press, Stanford, California.
Tveten, John and Gloria (1996), Butterflies of Houston & Southeast Texas, University of Texas Press, Austin.
Mark Etheridge
© 1997