What Do Swallowtail Caterpillars Eat?

When one species is genetically similar to another species, their populations can often be mistaken for one and the same. This is exactly what has happened with Papilio solstitius, a tiger swallowtail butterfly newly recognized as a separate species. Alongside its similarities to close cousins, this swallowtail also displays unique traits. The separate species was overlooked previously due in part to its late season emergence. You can find these beauties on the northeast coast in states like Vermont and New Hampshire.

Have you ever seen a swallowtail butterfly? Swallowtail butterflies get their name from their long tail that extends from their hind wings. The tail serves as a diversion, attracting birds’ attention away from their head. Certain species of swallowtail also protect themselves by being distasteful to predators. As caterpillars, they feed on poisonous plants, so they won’t be an appealing snack to predators. There are close to 560 different species of swallowtail butterflies, and they all have unique dietary habits. But what do swallowtail caterpillars eat? Read on to find out.

This post was updated on May 19, 2025 to include information on a new species of swallowtail.

What Does a Swallowtail Caterpillar Look Like?

Swallowtails belong to the family Papilionidae and are known for having large, thick bodies. Swallowtail caterpillars go through five different stages (instars) over the course of 10 to 30 days and can reach up to two inches long before pupating. Swallowtail larvae survive by resembling bird or lizard droppings. Some species have the advantage of having rows of blue spots on the abdomen, which are known as fleshy tubercles.

Older larvae have enlarged thoraxes and eye spots that aid in survival. Some swallowtail caterpillars even have a defensive gland called the osmeterium. The defense gland sits directly behind their heads. It’s hidden from view and vibrantly colored.

What Do Swallowtail Caterpillars Eat?

The world is full of all sorts of swallowtail butterfly species. That means when the time is right, plenty of swallowtail caterpillars are searching for food. Swallowtail caterpillars eat plants from the birthwort, citrus, carrot, and custard-apple families. Young caterpillars also eat plants from the magnolia, olive, laurel, and rose families. However, some species have slightly different diets from others.

Pipevine Swallowtail Diet

The pipevine swallowtail occurs in northern and central Florida. At least three generations are produced every year. Female pipevine swallowtails lay orange-colored eggs on host plants. The pipevine swallowtail caterpillar enjoys eating Virginia snakeroot and vines in the birthwort family. They also feed on Dutchman’s pipe.

Zebra Swallowtail Diet

Zebra swallowtail species are widely distributed in the eastern and southeastern United States, including states such as Florida, Texas, Iowa, Wisconsin, Michigan, Pennsylvania, and New Jersey.

The zebra swallowtail eats shrubs in the custard apple family. They also eat a variety of pawpaw plants. Some of their favorite pawpaws include woolly, big flower, small flower, dwarf, and netted pawpaw.

Females lay pale green eggs on the shoots of young host plants. The caterpillars eat new growth from the plants along with the flowers. Zebra swallowtail larvae hide on the undersides of leaves and inside flowers. When disturbed, the caterpillar will enlarge its body to scare away danger.

Giant Swallowtail Diet

The giant swallowtail lives in Florida, California, and Colorado. They also live in Nebraska, Iowa, Southern Wisconsin, Michigan, New York, and Massachusetts.

Young caterpillars are brown except for a white and yellowish patch in the middle. They tend to have shiny skin. Giant swallowtail butterflies lay orange-colored eggs. The tiny caterpillars rest on the upper surface of the leaves.

The giant swallowtail caterpillar feeds on herbs and shrubby trees in the citrus family. They enjoy eating sea torchwood, common hoptree, and wild lime. Young swallowtail caterpillars also feed on lemon, tangerine, sweet orange, and grapefruit.

Larger caterpillars will rest on the branches or trunks of the host plant. Sometimes, giant swallowtail caterpillars are called orange dogs. They can completely defoliate small citrus trees and shoots.

How Does a Swallowtail Caterpillar Eat So Much?

In one day, a hungry swallowtail caterpillar can eat twice its weight in food. How do these tiny larvae eat so many plant leaves? It has to do with how the caterpillar’s body expands as it eats. As it stretches to the limit, the caterpillar’s exoskeleton splits behind its head. At this time, the larvae will begin to shed their cover. After anchoring its feet down with a silk pad, the caterpillar starts to shrug off its cover.

The process of removing their cover is called molting. A caterpillar will molt about four to five times. When a swallowtail caterpillar molts, it almost doubles in size. Soon, the fully grown caterpillar can turn into a butterfly.

Female Butterflies Carefully Select Host Plants

Female swallowtail butterflies carefully select host plants before laying their eggs. In some cases, a female may impersonate other species to help provide protection. One female swallowtail butterfly can lay as many as 1,500 eggs in her lifetime. They usually fly miles to find the perfect host plant to lay their eggs on. The butterfly identifies host plants using special sensors on its antennas and feet.

To help protect the eggs from sun, rain, and hungry predators, the female will lay the eggs on the underside of leaves and flowers. Stems also provide good protection for caterpillar eggs. A fluid released within the eggs helps glue them onto their host plant. The fluid can also help the eggs avoid drying out.

It might seem like a butterfly’s lifespan is short. However, an adult butterfly can live anywhere from one week up to 45 days. However, the exact lifespan depends on the swallowtail species.

Finding Swallowtail Caterpillars

Spotting swallowtail caterpillars requires patience and observational skills. Swallowtail butterflies are host-specific and seasonal. You have to know the right host plants for the species you’re looking for. You also need to know the prime caterpillar season.

For most swallowtail species, the caterpillar season occurs between February and November. Usually, female butterflies don’t select the most prominent plants to lay their eggs on. Instead, they’ll choose isolated plants that aren’t likely to contain predators.

What is the Host Plant for the Swallowtail Caterpillar?

Typical host plants for these species include the tulip tree (Liriodendron tulipifera), wild black cherry (Prunus serotina), and sweet bay magnolia (Magnolia virginiana).

In contrast, the western swallowtail (Papilio rutulus), which closely resembles them, primarily feeds on cottonwoods, aspens, and various other plants.

The food sources, or host plants, for black swallowtail larvae or caterpillars include parsley, dill, and carrot tops. Additionally, these caterpillars can also feed on Queen Anne’s lace, fennel, and turnips as alternative food sources.

Signs of Caterpillar Activity

How can you tell if a caterpillar is nearby? Caterpillar activity includes chewed leaves, nests, silk, and trails. Try paying attention to the leaves close to the ground since this is where most caterpillars are likely to be.

If you can’t find any caterpillars but you see signs of activity, a predator may have gotten to them first. It’s also possible that the larva has already finished feeding and made its way to the pupation sites.

If you want to raise a caterpillar into a butterfly, then one of the best ways to gather caterpillars safely is by laying a white sheet below their host plant. Shake the overhanging branches to dislodge the caterpillars onto the sheet. Be prepared to collect a few spiders, beetles, and other critters, too. Also, make sure you know the difference between a centipede and a caterpillar so you collect the right specimen. Finally, gather sprigs of host plants so you can feed your new pet caterpillar.