Eastern Tiger Swallowtail – Papilio glaucus

Eastern Tiger Swallowtail Papilio glaucus butterflies are found in all states east of the Continental Divide and in part of Canada. It and the Giant Swallowtail are the two largest butterflies in the United States. Host plants include black cherry (Prunus), sweetbay (Magnolia), tulip tree (Liriodendron), mountain ash (Sorbus), ash (Fraxinus), birch (Betula), cottonwood (Populus), and willow (Salix). In captivity, they eagerly lay eggs and mature on hop tree (Ptelea trifoliata). We use black cherry, poplar, hop tree, and sweet bay to raise them in captivity.

Eastern Tiger Swallowtail Papilio glaucus drinking nectar from wild plum blooms flowers

Eastern Tiger Swallowtail
Drinking nectar from wild plum blooms

Females are either yellow and black or black and black with blue at the bottom of their hindwings. The above photo is of a female yellow form Eastern Tiger Swallowtail. The photo below is of a black form female Eastern Tiger Swallowtail.

Eastern Tiger Swallowtail Papilio glaucus drinking nectar from spanish needles blooms flowers

Female Eastern Tiger Swallowtail
Drinking nectar from Spanish Needle flowers

Female Eastern Tiger Swallowtail blue scales on hind wings

Female Eastern Tiger Swallowtail
Blue scales on hind wings

Male Eastern Tiger Swallowtail butterflies have only a small patch of blue on their hind wings.

Eastern Tiger Swallowtail Papilio glaucus drinking nectar from porterweed blooms flowers

Male Eastern Tiger Swallowtail
Drinking nectar from Porterweed blooms

Eggs are green, smooth, and larger than many other species.

Eastern Tiger Swallowtail Papilio glaucus butterfly green egg

Eastern Tiger Swallowtail green butterfly egg

Eastern Tiger Swallowtail caterpillar eating its egg shell Papilio glaucus

Eastern Tiger Swallowtail caterpillar
Eating its egg shell

Young Eastern Tiger Swallowtails are often confused with young Black Swallowtail caterpillars. Many swallowtail caterpillars look very similar when young.

Eastern Tiger Swallowtail young caterpillar  Papilio glaucus

Eastern Tiger Swallowtail young caterpillar

Young swallowtail caterpillars are often called ‘bird poop’ caterpillars. Resembling animal excrement, this young caterpillar resembles lizard poop. Can you tell which is which?

Eastern Tiger Swallowtail butterfly caterpillar next to lizard poop

Eastern Tiger Swallowtail butterfly caterpillar
Can you tell which one is lizard poop?

Eastern Tiger Swallowtail butterfly caterpillar just finished molting

Eastern Tiger Swallowtail caterpillar finished molting

When not eating, caterpillars often sit on a silk hammock just above the leaf. Created from silk from their spinnerets just under their head, the hammock holds the caterpillar above the leaf surface.

Eastern Tiger Swallowtail butterfly caterpillar sitting on silk hammock on leaf

Eastern Tiger Swallowtail butterfly caterpillars
tend to rest on a silk hammock they make
just above, not touching the leaf.

Blue spots decorate the sides of some instars of Eastern Tiger Swallowtail caterpillars.

Eastern Tiger Swallowtail butterfly caterpillar blue spots fake eyes

Eastern Tiger Swallowtail butterfly caterpillar
Sports blue spots and fake eyes

Fake eyes are on the thorax of a caterpillar. Caterpillars have twelve simple eyes, six on each side of their heads. These eyes basically can only tell dark from light.

Eastern Tiger Swallowtail head parts six twelve eyes

Eastern Tiger Swallowtail head is light blue.
Six eyes are on each side of its head.

As the caterpillar grows, it become primarily green. The head is a tiny and blue.

Eastern Tiger Swallowtail head is light blue and body is green

Older caterpillars:
Head is light blue and body is green

When disturbed, it tucks its head down and extends its osmeterium, a gland that produces a scent that most people consider a bad odor.

Eastern Tiger Swallowtail orange osmeterium

Eastern Tiger Swallowtail orange osmeterium

Eastern Tiger Swallowtail green caterpillar larva

Eastern Tiger Swallowtail green caterpillar
Tiny blue head is visible at front

Caterpillars attach themselves in a ) shape, supported by its rear and a silk girdle. They pupate the next day into a brown chrysalis, resembling a broken twig. The number of generations per year depends upon where they are located. They spend the winter in diapause as chrysalises. In the spring, adult butterflies emerge to begin the cycle again.

Eastern Tiger Swallowtail chrysalis pupa

Eastern Tiger Swallowtail chrysalis

Eastern Tiger Swallowtail Papilio glaucus Indigo Spires Salvia

Eastern Tiger Swallowtail
Drinking from Indigo Spires Salvia

Eastern Tiger Swallowtail Papilio glaucus Male drinking from compost pile for salts

Eastern Tiger Swallowtail Male
Drinking from compost pile for salts

Eastern Tiger Swallowtail Papilio glaucus Male drinking from mud at the lake for salts

Eastern Tiger Swallowtail Male
Drinking from mud at the lake for salts

Eastern Tiger Swallowtail Papilio glaucus Forewings can move independent of hindwings

Eastern Tiger Swallowtail
Forewings can move independent of hindwings

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