The Eastern Tiger Swallowtail (Papilio glaucus) is one of six native swallowtail butterflies in the Great Lakes Region, with populations concentrated in the areas surrounding Lake Erie. It is found throughout the Long Point Basin and other southern areas, such as Rondeau, Skunk’s Misery, the AuSable River Basin, and Pinery Provincial Park, all within the the Eastern Deciduous Forest Region (Carolinian Life Zone). Around Long Point, it most often occurs within deciduous forests, oak savannas, swamps, meadows, and riparian forests. With enough flowers, it is also a common garden species. The Canadian Tiger Swallowtail (Papilio canadensis) is a very similar species distributed directly north of Eastern Tiger Swallowtail, with large populations in the coastal regions surrounding Lake Superior, northern Lake Huron, and interior northern regions, such as Algonquin Provincial Park. In the tension zone between the distributions of these two species is a natural hybrid – the Midsummer Tiger Swallowtail (Papilio solstitius). Other swallowtail species include the Spicebush Swallowtail (Papilio troilus), the Black Swallowtail (Papilio polyxenes), and the Giant Swallowtail (Papilio cresphontes) – North America’s largest butterfly. Occasionally, the Pipevine Swallowtail (Battus philenor) and Zebra Swallowtail (Eurytides marcellus) will occur in the region surrounding Lake Erie, but these are much rarer than the other species.

Description

The Eastern Tiger Swallowtail have wingspan of around 10-14 cm (in . Males are typically yellow with black stripes, and females are dimorphic, either similar in plumage to males, or mainly black, similar to a Spicebush and Pipevine Swallowtails. The dark morph of females is a classic example of Batesian mimicry, utilized for protection against predators. Like all lepidopterans (butterflies and moths), the Eastern Tiger Swallowtail has 4 life stages; egg, larvae, pupa, and adult. Each summer, 1 to 3 generations of Tiger Swallowtails occur each year. Females will lay their eggs on the leaf of a host plant near a nectar source. Host plants are typically trees including cottonwoods (Populus deltoides), White Ash (Fraxinus americana), Green Ash (Fraxinus pennsylvanica), Yellow Birch (Betula lutea), Black Cherry (Prunus serotina), Sassafras (Sassafras albidum), Tuliptree (Liriodendron tulipifera), and Magnolia (Magnolia accuminata). When the caterpillars emerge from their eggs they will feed on the leaves of the host plant. The caterpillars grow rapidly for about 3-4 weeks before pupating, with 5 instars. Depending on the season of pupation, the chrysalis will either grow and emerge as a butterfly within 9-11 days, or they will overwinter as a chrysalis. Larvae hatched in the autumn will often overwinter or “hibernate” as a pupa, usually finding refuge in leaf litter as it can produce shelter and insulation during the cold months. The pupa will pause its development until temperatures rise in the spring. They will produce glycerol and trehalose which acts as an antifreeze, preventing them from freezing. After the pupa stage, the adult butterfly emerges and is hungry for nectar. Preferred nectar sources are native wildflower species, especially Butterfly Milkweed (Asclepias tuberosa), Common Milkweed (Asclepias syriaca), Bee-balm (Monarda sp.), Echinacea Coneflowers (Echinacea sp.), Blazing Stars (Liatris), and vervains (Verbena sp.). Adult butterflies live for around 12 days. In that time, the butterfly must eat, mate, and reproduce before it perishes. Males will exhibit a puddling behaviour, where they land on damp soil or mud puddles to consume important minerals, such as sodium ions and amino acids. These chemicals are incorporated into the butterfly’s sperm –  increasing the reproductive fitness of male Eastern Swallowtails. During mating, the male Eastern Swallowtail transfer these important chemicals to the female, increasing egg viability. Afterwards, female Eastern Tiger Swallowtail Butterflies will look for the larval hosts plants.

Swallowtails have evolved multiple adaptations to avoid predators; which include birds, insects, spiders, wasps (Vespidae), and ants (Formicidae). Caterpillars are green, and mimic the appearance of bird droppings (early instars), or a small snake (later instars), with many species developing large eyespots on the thorax, deterring predators. When threatened, many of these species will retract their head, exposing their osmeterium – a bright yellow or orange organ at the back of the head. This organ releases a foul-smelling, often acidic, mixture of terpenes and other organic compounds. This noxious odor and taste act as a strong deterrent to ants, small spiders, wasps, and even some birds. Adult swallowtail butterflies rely on agility and camouflage to deter predators.

 

Fun facts 

• When puddling, dozens of male butterflies can often be observed in one spot if a soil or puddle is especially rich in minerals!
• Swallowtails, like many reptiles, can regulate their body temperature through basking on warm, sunny mornings, and escaping to dense forests during the hottest part of the afternoon!
• The probiscis (tongue) of an Eastern Tiger Swallowtail is 2-3 cm long, adapted for accessing long, tube-like flowers, such as those produced by Scarlet Bee Balm (Monarda didmya). Many of these wildflowers are a rich source of nectar for swallowtails.

 

Eastern Swallowtails face many challenges – what can we do to help the butterflies?

• Plant native wildflower species in your garden. Common milkweed and butterfly weed are butterfly-loving flowers!
• Leave the leaves alone in naturalized spaces! Overwintering pupae rely on a thick layer of fallen leaves to provide adequate insulation in the colder months.
• If you are a landowner, consider naturalizing part of your property and restoring native habitat!

 

Formalized with editing and added content by Matthew Palarchio in June 2025.

First written by Emily Ratch, Stewardship and Outreach Technician in November 2022, as a short article for Long Point Basin’s blog.

Photo Credits: Matthew Palarchio (yellow morph Tiger Swallowtail), Stock Photo retrieved from Canva (caterpillar), Stock Photo from Canva (dark morph female Tiger Swallowtail)

 

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To view a directory of all species featured on our website, visit: https://longpointlandtrust.ca/featured-species