common name: zebra swallowtail
scientific name: Eurytides marcellus (Cramer) (Insecta: Lepidoptera: Papilionidae)
The zebra swallowtail, Eurytides marcellus (Cramer), is our only native kite swallowtail (tribe Leptocircini [=Graphiini]). Two other species rarely stray into Texas and Florida. The zebra swallowtail is one of our most beautiful swallowtails. Unlike most of our other native swallowtails, they are not involved in a mimicry complex. The zebra swallowtail has also been called the pawpaw butterfly, kite swallowtail and ajax.
Figure 1. Adult summer form of the zebra swallowtail, Eurytides marcellus (Cramer). Photograph by Jerry F. Butler, University of Florida.
The zebra swallowtail is widely distributed from southern New England west to southern Minnesota and south to eastern Texas and Florida.
The wingspread of males is 3.0 to 4.6 cm and females 2.9 to 4.9. cm. The upper surface of the wings is white with black stripes. The hindwings have very long tails. The zebra swallowtail exhibits seasonal dimorphism. Early spring specimens are lighter in color, smaller, and have tails only about half as long as summer forms.
Eggs are pale green. Young larvae are dark colored with many transverse black, yellow, and white bands. Older larvae are green with broad blue, black, and yellow transverse bands between the thorax and abdomen and usually yellow bands between abdominal segments and numerous fine transverse black lines on thorax and abdomen. However, larvae exhibit color polymorphism. The osmeterium is yellow. Pupae are green or brown with light lines simulating a leaf-like texture and are supported with a silken girdle.
Figure 2. Young larva of zebra swallowtail, Eurytides marcellus (Cramer), in Asimina angustifolia Raf. flower.Photograph by Jerry F. Butler, University of Florida.
Figure 3. Full-grown larva of zebra swallowtail, Eurytides marcellus (Cramer), with osmeterium extruded. Photograph by Jerry F. Butler, University of Florida.
Figure 4. Pupa of the zebra swallowtail, Eurytides marcellus (Cramer). Photograph by Jerry F. Butler, University of Florida.
There are two flights in the North and many flights in Florida from March to December. Males patrol for females in the vicinity of host plants, and females frequently may be observed ovipositing on host foliage. Adults seek nectar at a variety of flowers and also obtain moisture from mud.
Females select plants with young leaves for oviposition. Eggs are laid singly on the young leaves, and larvae feed on foliage (and flowers when available). This requirement for new leaves may limit reproduction of E. marcellus in summer and fall. Production of new leaves is often stimulated during this period by defoliation of the host plant by the pyralid moth, Omphalocera munroei Martin. Therefore, abundance of late flights of E. marcellus may be dependent on abundance of this moth.
Larvae have an extrusible osmeterium that is coated with strongly smelling chemicals (isobutyric and 2-methyl butyric acids). When disturbed, they extrude the osmeterium and smear the offender with the chemicals. This has been shown to be an effective defense against small ants and spiders, but not against most other predators. Osmeterial defense is also ineffective against the ichneumonid parasitoid of papilionids, Trogus pennator (Fabricius), which does not trigger extrusion of the osmeterium with its attacks. Other defensive measures utilized by the larvae are to drop off the host plant when disturbed by a potential predator and for third, fourth, and fifth instar larvae to rest off the plant in leaf litter when not feeding.
Pupation usually occurs on the under sides of leaves of the host plant. Some pupae of each flight overwinter. Short photoperiod produces diapausing pupae that hibernate.
The host plants are Asimina species (pawpaws) (Annonaceae). Throughout most of the range of the zebra swallowtail, Asimina triloba (L.) Dunal is the only host. In the southeast U.S., a variety of other Asimina species are utilized.
Figure 5. The slimleaf pawpaw, Asimina angustifolia Raf. (Annonaceae) is a commonly-used host in central Florida for the zebra swallowtail, Eurytides marcellus (Cramer). Photograph by Donald W. Hall, University of Florida.
Figure 6. Smallflower pawpaw, Asimina parviflora (Michx.)Dunal (Annonaceae), a larval host for the zebra swallowtail, Eurytides marcellus (Cramer). Photograph by Donald W. Hall, University of Florida.
Figure 7. Common pawpaw, Asimina triloba (L.)Dunal (Annonaceae), is a larval host for the zebra swallowtail, Eurytides marcellus (Cramer). Photograph by Donald W. Hall, University of Florida.
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