Species of the Month, November 2022: Eastern Tiger Swallowtail

Eastern Tiger Swallowtail (Papilio glaucus)

By: Emily Ratch
Stewardship and Outreach Technician


Yellow and black swallowtail butterfly drinks nectar from purple flower
Eastern Tiger Swallowtail on Ironweed

The Eastern Tiger Swallowtail is a native butterfly to eastern North America, including southern Ontario. This common butterfly has a wingspan of around 3 to 5 inches. Males are typically yellow with black stripes, and females are dimorphic, meaning they can be either yellow with black stripes, or black. These butterflies also use the dark morph as a mimicry tactic to protect themselves from predators, mimicking the poisonous pipeline swallowtail (usually in the south). 

A female may have 1 to 3 generations in a year.

Like most insects, the Eastern Tiger Swallowtail has 4 life stages; egg, larvae, pupa, and adult.

Females will lay their eggs on the leaf of a host plant near a nectar source. Host plants are typically trees including cottonwoods, ash, birch, black cherry, tulip trees, and magnolias. When the caterpillars emerge from their eggs they will feed on the leaves of the host plant. The caterpillars live for about 3-4 weeks before pupating.

Green tiger swallowtail caterpillar on leaf
Tiger Swallowtail caterpillar

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 fall 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.

This is why it’s so important to leave the leaves alone in backyards and gardens. 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. The butterfly lives for around 12 days. In that time, the butterfly must eat, mate, and reproduce before it perishes.

This butterfly relies on native plant species such as milkweeds, butterfly weed, and asters, usually being most attracted to red and pink flowers. The nectar provides vital nutrition for the butterfly. The Eastern Tiger Swallowtail is commonly found in deciduous forests, woodlands, fields, rivers, waterways and gardens. 

The Eastern Tiger Swallowtails are faced with many challenges in their lifetime, predators, habitat loss, and lack of native food sources. 

So what can we do to help?

  • Do your part and plant native species in your garden. Common milkweed and butterfly weed are butterfly-loving flowers. 
  • Leave the leaves alone! Overwintering pupae rely on a thick layer of fallen leaves to provide adequate insulation in the colder months.

    Two yellow and black Tiger Swallotwail butterflies on thistle flower
    A pair of Tiger Swallowtail butterflies on thistle






Image credits:  Flickr (no known copyright)

Brianne Curry

Outreach & Fund Development Manager