Eastern Tiger Swallowtail or Western: Understanding Butterfly Differences

folder_openInsecta, Lepidoptera
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The Eastern and Western Tiger Swallowtails are two stunning butterfly species found in different regions of North America. Both are known for their beautiful colors and large size, making them a delightful sight in gardens and nature. While they share some similarities, each has distinct characteristics that set them apart.

The Eastern Tiger Swallowtail, scientifically known as Papilio glaucus, is predominantly found east of the Mississippi River and into the Great Plains states, with additional populations in some Mexican states. In contrast, the Western Tiger Swallowtail, or Papilio rutulus, is typically found in the western United States and Canada.

Both species are known for their striking yellow and black patterned wings, but subtle variations in color, size, and habitat preferences exist. The Eastern species tend to have more blue accents on their wings, whereas the Western species have a more pronounced yellow hue. Additionally, Western Tiger Swallowtails are generally found in wetter areas across their range.

Overview of Eastern and Western Tiger Swallowtail

Tiger Swallowtail Butterfly Species

There are various species of tiger swallowtail butterflies, including the Eastern Tiger Swallowtail (Papilio glaucus), Western Tiger Swallowtail (Papilio rutulus), Canadian Tiger Swallowtail (Papilio canadensis), and Two-tailed Tiger Swallowtail (Papilio multicaudata).

Physical Characteristics

Eastern Tiger Swallowtail:

  • Adults are yellow with four black bands on the front wings1
  • Males have more yellow, while females can also have a dark form2

Western Tiger Swallowtail:

  • Adults are yellow with black banding and broad black edge on wings3
  • Similar to the Eastern species, but with slightly different banding pattern4

Here’s a comparison table of their physical characteristics:

Feature Eastern Tiger Swallowtail Western Tiger Swallowtail
Color Yellow with black bands Yellow with black bands
Dark form Only in females N/A
Wingspan 7.9 to 14.0 cm 7.0 to 10.0 cm

Geographical Distribution

  • The Eastern Tiger Swallowtail is found east of the Mississippi River and into the Great Plains states5
  • Western Tiger Swallowtail is found mostly in western North America6

Key Differences Between Eastern and Western Tiger Swallowtail

Wing Patterns and Colors

Eastern Tiger Swallowtails are predominantly yellow with four black bands on their front wings 3. In contrast, Western Tiger Swallowtails exhibit similar patterns, but with noticeable differences, such as more irregular and bolder black lines. Additionally, male Eastern Tiger Swallowtails have more conspicuous blue patterns on their hind wings, particularly on the edges.

Size and Wingspan

The Eastern Tiger Swallowtail exhibits a wingspread range of 7.9 to 14.0 cm (approx. 3.12 to 5.5 inches)4. Although similar in size to their Eastern counterparts, Western Tiger Swallowtails are generally slightly smaller.

Tiger Swallowtail Species Wingspan Range
Eastern Tiger Swallowtail 3.12 to 5.5 inches
Western Tiger Swallowtail Slightly smaller

Reproductive Behavior

Eastern Tiger Swallowtails lay their eggs on a specific family of plants, such as wild cherry, plums, and other fruit trees. While Western Tiger Swallowtails also have preferences for certain host plants, their larvae can consume a wider range of foliage from flowering species5.

To sum up:

  • Eastern Tiger Swallowtails are more yellow, with more distinct blue patterns on male hind wings.
  • Western Tiger Swallowtails have more irregular and bolder black lines on wings.
  • Eastern Tiger Swallowtails on average have a larger wingspan.
  • Western Tiger Swallowtails have larvae with a wider range of host plants.

Life Cycle and Host Plants

Eggs and Caterpillars

Eastern and western tiger swallowtails both lay their eggs on host plants where their caterpillars will feed. Some common host plants for eastern tiger swallowtails include tulip trees, magnolia, and wild cherry. In contrast, western tiger swallowtails prefer cottonwood, willow, and ash.

Caterpillars of eastern tiger swallowtails feed primarily on leaves, while western tiger swallowtails show a preference for sweet bay and other wetland plants.

Eastern Tiger Swallowtails:

  • Host plants: tulip trees, magnolia, wild cherry
  • Caterpillars feed on leaves

Western Tiger Swallowtails:

  • Host plants: cottonwood, willow, ash
  • Caterpillars feed on sweet bay and wetland plants
    Eastern Tiger Swallowtails Western Tiger Swallowtails
    Tulip trees, magnolia, wild cherry Cottonwood, willow, ash
    Leaves Sweet bay, wetland plants

Adult Butterflies and Nectar Sources

Eastern tiger swallowtails visit a wide variety of flowers to obtain nectar. A popular choice among gardeners wishing to attract these butterflies are zinnias, which are endorsed by the North American Butterfly Association.

Western tiger swallowtails, on the other hand, are known to feed on nectar from many flowering species. Adults of this species take flight from June through July and, in Pacific coastal areas, may be found throughout much of the year.

Eastern Tiger Swallowtails:

  • Obtain nectar from various flowers
  • Attracted to zinnias

Western Tiger Swallowtails:

  • Feed on nectar from many flowering species
  • Active from June to July, year-round in Pacific coastal areas
    Eastern Tiger Swallowtails Western Tiger Swallowtails
    Various flowers, zinnias Many flowering species
    Throughout the year June to July, year-round in Pacific coastal areas

Additional Information and Resources

Identifying Swallowtail Species

There are several species of swallowtail butterflies, but two of the most common are the Eastern Tiger Swallowtail and the Western Tiger Swallowtail. To help identify these species, consider their ranges and physical features:

Ranges

  • Eastern: East of the Mississippi River and into the Great Plains
  • Western: Pacific coastal areas

Physical Features

  • Two-tailed: Both species have two tails on each hindwing
  • Canadian Tiger: A closely related species to the Eastern Tiger Swallowtail

Comparing Eastern and Western Tiger Swallowtails:

Features Eastern Tiger Swallowtail Western Tiger Swallowtail
Range East of Mississippi & Great Plains Pacific coastal areas
Two-tailed presence Yes Yes
Canadian Tiger species Related Not related

Conservation and Gardening Tips

Swallowtail butterflies are an essential part of our ecosystem and can be supported by creating an attractive garden for them:

  • Plant host plants for caterpillars, like wild black cherry
  • Provide nectar-rich flowers for the adult butterflies
  • Offer a water source and a shallow dish filled with water and stones
  • Conserve sodium sources, like water with dissolved salts

To learn more about conserving swallowtail species and creating an ideal habitat, explore resources like this one.

Footnotes

  1. https://edis.ifas.ufl.edu/publication/IN218
  2. https://www.fs.usda.gov/wildflowers/pollinators/pollinator-of-the-month/TigerSwallowtail.shtml
  3. https://www.butterfliesandmoths.org/species/Papilio-rutulus 2
  4. https://texasinsects.tamu.edu/western-tiger-swallowtail/ 2
  5. https://www.fs.usda.gov/wildflowers/pollinators/pollinator-of-the-month/TigerSwallowtail.shtml 2
  6. https://www.butterfliesandmoths.org/species/Papilio-rutulus

Authors

  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

    View all posts
  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

    View all posts
Tags: Tiger Swallowtails

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6 Comments. Leave new

  • dorwageld@aol.com
    August 22, 2012 9:20 pm

    Beautiful photos of a stunning butterfly! And although this is slightly off topic, I too, have that same color buddleia in my yard. It volunteered the year after I planted a Black Knight and a Pink Delight in close proximity to each other. I have always wondered how it came to be, as I’ve never had any other unintended buddleia. It is an absolute MAGNET for butterflies and bees of all kinds, wasps, skippers, flower flies, spiders, clearwing moths, as well as ruby-throated hummingbirds. Have a lovely evening! -Dori Eldridge

    Reply
  • I’ve been seeing waaaaaay more swallowtails of all species this year in Silver Lake. I think I’ve even seen a few Giant Swallowtails in the past few weeks. They were huge. I got a few good shots of a Western Tiger earlier this year:
    http://redcarproperty.blogspot.com/2013/08/red-car-property-neighborhood.html
    http://redcarproperty.blogspot.com/2013/02/corralitas-drive-western-tiger.html

    Reply
    • This has been a good year for Swallowtails Diane. The Western Tiger Swallowtails appeared a bit earlier than usual and we have been getting sightings of Giant Swallowtails the past few weeks. Sadly, the Anise Swallowtails have not been plentiful even though we grow carrots in the garden.

      Reply
  • I’ve been seeing waaaaaay more swallowtails of all species this year in Silver Lake. I think I’ve even seen a few Giant Swallowtails in the past few weeks. They were huge. I got a few good shots of a Western Tiger earlier this year:
    http://redcarproperty.blogspot.com/2013/08/red-car-property-neighborhood.html
    http://redcarproperty.blogspot.com/2013/02/corralitas-drive-western-tiger.html

    Reply
  • I found one that looks similar today in Tacoma , WA

    Reply
  • Today I found a Western Tiger Swallowtail Caterpillar. It was crawling across a concrete patio in our residence in Santa Fe, NM.
    It is quite ugly in its Pupa stage but photos I see of it in it’s adult state is is very attractive. I believe that I will release it from the small glass vial in which I captured it to prevent being killed by our two curious dogs. I wasn’t successful in getting a photo of it. It’s approximately 2 inches long rust colored body with a thin red,(apprx 1/64th inch wide, closest to the head and farthest from any feet or legs, next to a yellow band perhaps 3 times that width and then near a black band perhaps 1/16th inch wide. The body has several bublous bands with feet on the underside.
    I find several references to these being from Mexico and Canada.
    Really ugly

    Reply

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