Wildlife Watching – Western Tiger Swallowtail

Description:

• A large, bright yellow butterfly with black stripes and small blue and orange dots at the base of its wings.
• It has triangular wings that are 7-10cm long, that taper to a fork, making the butterfly look like it has a swallow-like tail.

Habitat:

• This type of butterfly loves open sunny places, meadows, forest edges, riverbanks, riparian areas, and backyard gardens.

Behaviour:

• In flight, Western Tiger Swallowtails mostly glide, with fewer wing beats compared to other butterflies.
• They often congregate in large numbers at mud puddles (a behaviour called “puddling”) to drink water and obtain mineral nutrients.
• Adult butterflies feed on flower nectar and are valuable pollinators.
• They lay eggs on the leaves of host plants such as aspens and willows. Only four days later, the caterpillars will hatch and spend two weeks feeding on the host plant before pupating. If it is late in the season, the swallowtails will overwinter in the chrysalis and emerge as butterflies the following summer.
• Western Tiger Swallowtails live 6-14 days in butterfly form.

Diet:

• Eggs are laid on ‘host plants’ including aspen, cottonwood and willows that caterpillars will feed upon after hatching.
• Adult butterflies consume flower nectar.

Connections:

• The Western Tiger Swallowtail is common and easy-to-spot thanks to its size, bright colours and tendency to fly in open sunny areas and urban gardens.
• A Butterfly Habitat Interpretive Garden opened in Syringa Provincial Park in 2023 to demonstrate the importance of native plants and native pollinators, like the Western Tiger Swallowtail. It was created in partnership between the Kootenay Native Plant Society and BC Parks and you visit the beautiful, informative site near the Bighorn Campground turnaround.

Cool Facts:

• The Western Tiger Swallowtail can hibernate in its chrysalis, emerging as a butterfly in the spring/summer.
• Hibernating swallowtails (in chrysalis) produce glycerol, an antifreeze compound, to help prevent them from freezing over the cold, winter months.
• Butterflies, including the Swallowtail can be distinguished from moths by their antennae: butterfly antennae are club-shaped with a bulb at the tip, while moths’ antennae are feathery or tapered at the tip. Butterflies also tend to hold their wings up vertically over their bodies (closed) at rest while moths hold theirs horizontally (open).