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Spicebush Swallowtail

Papilio troilus

Summary 5

The Spicebush Swallowtail (Papilio troilus) is a common black swallowtail butterfly found in North America, also known as the Green-Clouded butterfly. It has two subspecies, Papilio troilus troilus and Papilio troilus ilioneus, the latter found mainly in the Florida peninsula. The spicebush swallowtail derives its name from its most common host plant, the spicebush, members of the genus Lindera.

Description 5

Typically, the wingspan of a Spicebush Swallowtail ranges from 3-4 inches. Adults are primarily black/brown in color, with a trademark green-blue (male) or bright blue (female) splotch in the shape of a half moon on the hind-wings. The forewing has a border of cream-colored, oval spots. In the middle portion of the wing, the spots can be moon-shaped and a light blue in color. Both sexes have cream-yellow moon-shaped spots on the edges of the hind-wings and a bright, orange spot at the base of the wings. In females, the orange spot at the base of the wings will turn a greenish-white shade in summer, but not the spring.

On the underside of the hindwing, there will be a dual row of orange spots, which distinguishes it from the pipevine swallowtail, which only has a single row of spots. In between these rows, there is more blue or green coloring.

Larva Description 5

As larvae, Spicebush Swallowtails have two stages of mimicry. While the larvae are in the early stages, they are dark brown in color and thus appear to resemble bird droppings, which encourages predators to leave them alone. When the larvae have progressed to their fourth and last instar and are nearly ready to pupate, they turn a yellow-green color and are marked by two large black dots with a white highlight. The placement of these dots on the swollen thorax creates the illusion that the caterpillars are common green snakes. Mimicking snakes help the caterpillars to ward off predators, specifically birds. The caterpillar Spicebush Swallowtails enhance the physical resemblance behaviorally, as they have been observed to "rear up and retract the actual caterpillar head."

The osmeterium of the caterpillar also helps to enhance the resemblance to a snake. When attacked, the larvae will expose the osmeterium, a y-shaped organ typically folded up within the caterpillar. For many Spicebush Swallowtails, the osmeterium is red in color, thus creating the illusion of a snake tongue and even further enhancing the disguise.

Larval host plants 6

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.

Plant Foods: leaves; nectar

GTM Occurrence 7

The Spicebush Swallowtail is uncommon at the GTM. Most observations were along the Glasswort Loop (Transect C), with additional sightings in the open habitat (Transect A) and the Marsh Pond Overlook (Transect B). It is most abundant in July with other occurrences in May, June, and September. There have been 9 specimens observed as of December 28, 2015.

Distribution 5

The Spicebush Swallowtail is found from New England to Florida and west to Missouri, Oklahoma, and east Texas. There are scattered records from North Dakota south to Kansas and a few records from southeastern Colorado.

Habitat 8

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.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest

Wetlands: marsh ; swamp ; bog

Other Habitat Features: urban ; suburban ; agricultural

Nature serve conservation status 9

Rounded Global Status Rank: G4 - Apparently Secure

Sources and Credits

  1. (c) Lisa Brown, some rights reserved (CC BY-NC), http://www.flickr.com/photos/33695431@N00/2686733639
  2. (c) Dianne Frost, some rights reserved (CC BY-NC-ND), https://www.flickr.com/photos/dkfrost/6953951202/
  3. (c) Larry Meade, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/34323709@N07/3690715177/
  4. (c) Greg Schechter, some rights reserved (CC BY), https://www.flickr.com/photos/gregthebusker/3715717844/
  5. Adapted by GTMResearchReserve from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Papilio_troilus
  6. Adapted by GTMResearchReserve from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/25066222
  7. (c) GTMResearchReserve, some rights reserved (CC BY-SA)
  8. (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31412844
  9. (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28748844

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