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.

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.

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

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

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

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

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.

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

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.

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

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

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.