Papilio troilus

Geographic Range

Spicebush swallowtails (Papilio troilus) are found in eastern North America from southern Canada to Florida, and west to Oklahoma, Manitoba, and central Texas. This species is less common on the western edge of its range, along the southern Mississippi River, as well as in New England. Occasionally these butterflies are found as far west as Colorado, and as far south as Cuba. (Hall and Butler, 2000; Jaques and Sexton, 2004; Struttman, 2004; Tyler, 1975; Hall and Butler, 2000; Jaques and Sexton, 2004; Struttman, 2004; Tyler, 1975)


The larval form of P. troilus is found in deciduous woodlands, wooded swamps, and pine barrens. The adult form is a fairly common butterfly within its range, that can be seen in woodlands, parks, yards, fields, and roadsides, but prefers the borders of shady woods. Males are often found near moist, sandy areas along roads or streams. (Allen, 1997; Hall and Butler, 2000; Jaques and Sexton, 2004; Struttman, 2004; Tyler, 1975)

Physical Description

In adults, the upper surface of the forewing is mostly black, with ivory spots along the bottom margin. The upper surface of the hindwing has an orange spot on the costal margin which is unique to spicebush swallowtails. There is also a band of bluish (female) or bluish-green (male) scales on the upper surface of the hindwing. The bottom margin of the hindwing has bluish or ivory spots, and also a “tail” measuring 9 to 12 mm long at the bottom of the wing. This feature is similar to other swallowtails such as black swallowtails (Papilio asterius) and pipevine swallowtails (Battus philenor). However, the "tail" in P. troilus is broader and spatulate. Wingspan ranges from 80 to 115 mm.

The larval or caterpillar form initially resembles bird droppings, but in later instars is green with a pale yellow lateral line running the length of the caterpillar. The underside of the caterpillar is pinkish-brown, and each abdominal segment is ringed by six blue spots outlined in black. One dot on each side is below the yellow lateral line.

Caterpillars have two pairs of false eyespots: one pair is toward the back of the thorax, and is small and yellow. The other pair is closer to the head, and is yellow with a black spot in the middle, and a white spot that resembles the glare off a black eye. The combination of the eyespots and a swollen thorax is believed to be a mimicry of either green snakes or tree frogs.

Female caterpillars are often slightly longer than males. Pupae can be brown or green depending on the season, mimicking leaves of spring and fall, and have a pair of horns at the top of the pupa. (Allen, 1997; Hall and Butler, 2000; Jaques and Sexton, 2004; Nitao, et al., 1991; Saunders, 1932; Struttman, 2004; Tyler, 1975)

  • Sexual Dimorphism
  • female larger
  • sexes colored or patterned differently
  • Range wingspan
    80 to 115 mm
    3.15 to 4.53 in
  • Average wingspan
    100 mm
    3.94 in


Spicebush swallowtails lay their eggs on the undersides of leaves. Larvae hatch and initially resemble bird droppings, but come to mimic a snake, complete with eyespots, in later instars. These larvae form pupae which are green (summer) or brown (fall) and metamorphose into butterflies. Some pupae hibernate over winter, and these are usually brown to mimic dead leaves. Shorter photoperiods associated with the coming of winter trigger pupae to assume the brown color, regardless of whether the leaf they live on is green or brown.

Papilio troilus produces two generations per year from April to October, except in Florida, where three are possible between March and December. (Allen, 1997; Hazel, 1995; Struttman, 2004)


In order to find females, males patrol flyways on hilltops or host plant sites. When patrolling males meet, they generally fly in opposite directions. Females have much lower representations in these areas. The only areas of equal representation are nectar sources. When a female appears, a male flies towards her and performs a brief courtship ritual, lasting less than a minute. If the female is receptive to the courtship, copulation occurs, often lasting over an hour. Both males and females often copulate with multiple partners. A fertilized female oviposits in the warm portion of the day, laying eggs singly on young host leaves. (Allen, 1997; Lederhouse, 1995)

Spicebush swallowtails breed after becoming adults. This takes place during the summer months (April to October, or March to December in the southern part of the range) when there is ample food for the larvae. Though both males and females copulate with multiple partners, females are increasingly less likely to seek another mate with each successful copulation. Females search out host plants by visual and chemical cues, then land on a plant and drum the leaf with their forelegs to "taste" it, and confirm it as a host plant. (Lederhouse, 1995; Nishida, 1995; Struttman, 2004)

  • Breeding interval
    Males mate daily. A females may mate multiple times during her lifetime.
  • Breeding season
    Breeding occurs between April and October.

Care of eggs once they are laid, or of larvae, does not occur in this species. However, females do invest in their young by producing nutrient rich eggs to allow the larvae to develop until hatching. They also select host plants carefully, to help ensure the survival of their young. (Hall and Butler, 2000)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female


Adult swallowtail butterflies live roughly from 2 days to 2 weeks. (Lederhouse, 1995)

  • Typical lifespan
    Status: wild
    2 to 14 days


Caterpillars of P. troilus form a shelter out of a leaf by folding it over and spinning silk to form a nest inside the leaf. They feed nocturnally, and when disturbed, an orange scent gland behind their head releases a disagreeable odor. When the caterpillar completes its development, it pupates and becomes a chrysalis, before metamorphosing into a butterfly.

As adults, the butterflies fly around in search of mates and nectar. Adult males engage in a common practice among swallowtails called "puddling". They may congregate around moist, sandy areas along roads or streams, and sip moisture and minerals from the soil. (Allen, 1997; Bouseman and Sternburg, 2001; Hall and Butler, 2000; Jaques and Sexton, 2004; Struttman, 2004)

Home Range

Larvae are confined to the plant that their egg was laid on. Adults do not define a home range. They simply fly around in search of nectar and mates. (Hall and Butler, 2000; Jaques and Sexton, 2004; Struttman, 2004)

Communication and Perception

Females use both visual and chemical cues when finding hosts plants on which to oviposit. After landing on a plant, a female confirms the plant as a host plant by drumming the surface of the leaf with her forelegs, which have contact chemorecepters located on the foretarsi.

Information on communication between individuals is limited to mating contexts. Males apparently recognize females visually. The courtship display of a male involves many visual elements. In additon, during the process of mating itself, there is some contact, probably relaying information between the individuals. (Feeny, 1995; Nishida, 1995)

  • Other Communication Modes
  • mimicry

Food Habits

As in many animals that undergo metamorphosis, the diet of the young differs from the diet of the adult.

In P. troilus, larvae feed on the leaves of aromatic trees and shrubs in the family Lauraceae. Their primary hosts are spicebush (Lindera benzoin), sassafras (Sassafras albidum), but they are also known to feed on camphor (Cinnamomum camphora) sweetbay (Magnolia virginiana), and redbay (Persea borbonia). The choice of host plant depends primarily on host availability in a particular part of the range. There is evidence of geographic divergence among populations with larval adaptation to the most common host species.

Adult P. troilus butterflies feed on nectar, and are partial to honeysuckle, clover, and thistle flowers. Their unusually long proboscis allows them to reach nectar in unusually deep flowers such as bee balm. They will also drink nectar from other flowers such as jewelweed, milkweed, azalea, dogbane, mimosa, and sweet pepperbush. (Allen, 1997; Hall and Butler, 2000; Jaques and Sexton, 2004; Nitao, et al., 1991; Saunders, 1932; Struttman, 2004; Tyler, 1975)

  • Plant Foods
  • leaves
  • nectar


Although spicebush swallowtails employ extensive mimicry throughout their lifecycles, mimicking bird droppings and green snakes as caterpillars, and mimicking the poisonous pipevine swallowtail (Battus philenor) as adults, they suffer from extensive predation. Spiders, insect predators such as dragonflies and robber flies, and especially birds, will eat swallowtail butterfly adults and larvae. (Newton, 2004)

  • Anti-predator Adaptations
  • mimic
  • cryptic
  • Known Predators
    • Birds
    • Spiders
    • Dragonflies
    • Robber flies

Ecosystem Roles

Spicebush swallowtail larvae are specialist herbivores, feeding on members of the family Lauraceae. Adults are generic pollinators for many flowers, inadvertently pollinating while feeding on nectar. (Hall and Butler, 2000; Struttman, 2004; Tyler, 1975)

  • Ecosystem Impact
  • pollinates
Species Used as Host
  • Lauraceae (as larval food plants)
Mutualist Species
  • Angiosperms (as pollinators)

Economic Importance for Humans: Positive

Swallowtail butterflies have a slow and lazy flight, and because of this, they are easy to catch, making them prime collector's items. They are also popular photography subjects because of their large size, showiness, and slow flight. Since spicebush swallowtails are generic pollinators, they are also beneficial to crops. (Newton, 2004)

  • Positive Impacts
  • research and education
  • pollinates crops

Economic Importance for Humans: Negative

Spicebush swallowtails are not usually considered pests, though their host trees occasionally suffer slightly when planted as ornamentals. (Newton, 2004)

  • Negative Impacts
  • crop pest

Conservation Status

The Nature Conservancy ranks spicebush swallowtails as a G5 species, which means that they are in no danger on a global scale, though may be quite rare in parts of the species' range, especially on the periphery. (Struttman, 2004)

Other Comments

A subspecies of Papilio troilus, called Papilio troilus ilioneus, is the dominant type of this butterfly in Florida. The major distinguishing feature of this subspecies is that it has enlarged, light submarginal spots. (Harris, 1972)


James Mickley (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

Nancy Shefferly (editor), Animal Diversity Web.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


living in the southern part of the New World. In other words, Central and South America.

World Map


living in landscapes dominated by human agriculture.


Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.


uses smells or other chemicals to communicate


having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.


a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.

  1. active during the day, 2. lasting for one day.

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature


union of egg and spermatozoan


an animal that mainly eats leaves.


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


An animal that eats mainly plants or parts of plants.


the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

internal fertilization

fertilization takes place within the female's body


marshes are wetland areas often dominated by grasses and reeds.


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


imitates a communication signal or appearance of another kind of organism


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


an animal that mainly eats nectar from flowers


active during the night


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season


offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.


living in residential areas on the outskirts of large cities or towns.


a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.


A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.


living in cities and large towns, landscapes dominated by human structures and activity.


uses sight to communicate


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Bouseman, J., J. Sternburg. 2001. Field Guide to Butterflies of Illinois. Champaign, IL: Illinois Natural History Survey.

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Newton, B. 2004. "Swallowtails of Kentucky - University of Kentucky Entomology" (On-line). Kentucky Critter Files: Kentucky Insects. Accessed November 19, 2005 at

Nishida, R. 1995. Oviposition Stimulants of Swallowtail Butterflies. Pp. 17-26 in J Scriber, Y Tsubaki, R Lederhouse, eds. Swallowtail Butterflies: Their Ecology and Evolutionary Biology. Gainesville, FL: Scientific Publishers.

Nitao, J., M. Ayres, R. Lederhouse, J. Scriber. 1991. Larval Adaptation to Lauraceous Hosts: Geographic Divergence in the Spicebush Swallowtail Butterfly. Ecology, 72/4: 1428-1435. Accessed November 19, 2005 at

Saunders, A. 1932. Butterflies of the Allegany St. Park. Albany, NY: The University of the State of New York.

Struttman, J. 2004. "Butterflies of North America" (On-line). Northern Prairie Wildlife Research Center. Accessed November 19, 2005 at

Tyler, H. 1975. The Swallowtail Butterflies of North America. Healdsburg, CA: Natwegraph Publishers Inc..