If a butterfly the size of your hand glides through a sunny backyard in summer, it is almost certainly an Eastern Tiger Swallowtail (Papilio glaucus). Bright yellow wings with bold black tiger stripes make it one of the most recognizable insects in the eastern US.
What it looks like
Wings span 8 to 14cm across, larger than most songbirds. Males are always yellow with four vertical black stripes on each forewing and a row of yellow spots inside the black border. Each hindwing ends in a long pointed tail. Females come in two forms: a yellow form like the male, and a dark form that is mostly black with a faint shadow of the stripes. The dark form mimics the toxic Pipevine Swallowtail to fool predators.
When and where
- Season: April through October across the eastern US, with peak numbers in July.
- Habitat: Backyards with flowers, woodland edges, stream sides, suburban gardens.
- Best time: Warm sunny afternoons at zinnias, butterfly bush, milkweed, or any tall purple flower.
The puddle club
On hot summer days, groups of male Eastern Tiger Swallowtails gather on damp gravel, mud, or wet sand and stay there for hours sipping moisture. The behavior is called puddling, and it lets the males take in salts and minerals they pass to the female during mating. Females rarely puddle. The caterpillar is also worth meeting: it is bright green with two large fake eyespots that make it look like a small snake.
Spot one this weekend
Eastern Tiger Swallowtails are Common across the eastern US in summer. Plant or visit a stand of zinnias, milkweed, or coneflowers and wait. The flight is slow and gliding, so even a phone camera can usually catch a clear photo if you stand still for a minute.