Papilio glaucus (Eastern Tiger Swallowtail)
Species Overview
Scientific name: Papilio glaucus
Common name: Eastern Tiger Swallowtail
Family: Papilionidae
Range: Widely distributed in the eastern United States and southern Canada, including the Chicago area.
Identification: Large (3.5–5.5 inch wingspan) yellow butterfly with black tiger-like stripes; males have solid yellow hindwings with black borders, while females occur in both yellow and dark (mimic) morphs. Hindwings have characteristic "tails."
Ecological Role
Pollinator
Adults feed on nectar from a broad range of flowering plants, visiting both native and ornamental species.
Their large size and long proboscis allow them to pollinate deep or wide corollas that smaller butterflies cannot access.
Herbivore and host link
Larvae feed on foliage of several tree and shrub species, many of which are ecologically important to other insects and birds.
Caterpillars are part of the diet of birds, predatory insects, and parasitoid wasps.
Mimicry and predator interactions
Female dark morph mimics the distasteful Battus philenor (Pipevine Swallowtail) to deter predators, illustrating a notable case of Batesian mimicry in the Midwest.
Lifecycle
(Two broods per year in Chicago; three farther south)
Egg stage
Laid singly on host plant leaves, often near the edge.
Pale green or yellow when fresh.
Larval stage
Early instars resemble bird droppings for camouflage.
Later instars are green with large false eye spots, deterring predators by mimicking a snake’s head.
Feeds primarily on host plant foliage.
Pupal stage
Chrysalis color varies (green in summer, brown in overwintering generation).
Second-generation pupae overwinter in diapause.
Adult stage
Emergence in late spring; peak adult flight in Chicago is May–June and again in July–August.
Adults live 6–14 days, feeding heavily on nectar.
Best Native Host Plants (Chicago Region)
Papilio glaucus larvae feed primarily on woody species in the Lauraceae, Rosaceae, Oleaceae, and Magnoliaceae families. In the Chicago region, the best native hosts include:
Primary Larval Hosts
Tulip Tree (Liriodendron tulipifera) – excellent for supporting large populations; best in larger yards or parks.
Wild Black Cherry (Prunus serotina) – also supports many other Lepidoptera species.
Black Willow (Salix nigra) – important near water edges.
American Ash (Fraxinus americana, F. pennsylvanica) – still a host, but threatened by emerald ash borer; plant only if part of a monitored restoration.
Basswood (Tilia americana)
Secondary Larval Hosts
Eastern Cottonwood (Populus deltoides)
Hop Tree (Ptelea trifoliata) – smaller tree/shrub option.
Sassafras (Sassafras albidum) – native to parts of Illinois; aromatic leaves are a preferred host.
Best Native Nectar Plants for Adults
(Bloom periods matching adult flight times in Chicago)
Spring–Early Summer: Phlox divaricata, Zizia aurea, Aquilegia canadensis
Mid–Late Summer: Asclepias tuberosa, Monarda fistulosa, Eutrochium purpureum, Pycnanthemum virginianum, Solidago speciosa, Rudbeckia hirta, Vernonia fasciculata
Late Summer–Fall: Symphyotrichum novae-angliae, Solidago rigida
Habitat Support Tips for Chicago
Plant larval host trees near nectar-rich prairie perennials to provide both life stages with resources.
Maintain pesticide-free landscapes to avoid harming larvae and nectar plants.
If space is limited, choose smaller hosts like hop tree or sassafras rather than large canopy trees.
Include early-blooming and late-blooming nectar sources to cover both broods.
