Teach Outside
Resources and inspiration for current and aspiring outdoor educators and those interested in a natural learning environment.

Keeping Creatures- Anise Swallowtails


Keeping Creatures- Anise Swallowtails


 Swallowtail larva feeding on fennel.



Knife or Scissors

Paper Towels

Water Container


In the East Bay, California, we can find fennel growing readily in our parks, gardens, and alongside roadways. The anise swallowtail lays its eggs on the fennel and the larvae feed upon it when they hatch. Upon close observation, the small clear to green eggs (depending upon how old the eggs are) can be found stuck to the small leaves, or larvae of a variety of colors and sizes (depending upon how old the larvae are, how many instars they have experienced) can be found eating the stalks and leaves. If one wishes to observe the process of development (metamorphosis) up close, the fennel stalk can be cut and carefully carried back home.

Fill a vase or other container with water, and place the stalk of fennel inside.

Place the water container on top of a paper towel in an area of the room with indirect light so it doesn't overheat, such as on a counter or table. If there are many and/or voracious caterpillars, fresh stalks of fennel may need to be obtained often.

Growth and development are difficult processes, and it is entirely possible that your egg will fail to hatch or your caterpillar may fail to pupate or the pupa may not hatch. Be prepared to discuss the facts and reality of life and death!

As the larva eats, it poops, which is why the paper towel should be placed upon the surface where you keep the animal.

When the larva prepares to pupate, it may stay upon the fennel or it may possibly migrate to somewhere else in the house, such as the ceiling. If you are uncomfortable with this idea, you will probably want to keep the fennel setup inside a terrarium instead of on an open surface.

If temperature, humidity, light, and developmental conditions are just right, the pupa (chrysalis) will hatch into an adult swallowtail butterfly! It will hold itself upside down on the underside of the fennel leaves until its wings can grow and harden. Afterward, it could be taken outside and allowed to fly away. If you desire to keep it in the house a couple more days, you could fill a cotton ball with a sugar and water solution which mimics the nectar the butterfly needs to eat to survive. You would be able to observe its proboscis unfurling to pierce the cotton and sip the homemade nectar.


Information about fennel from California Invasive Plant Council.

iNaturalist information about anise swallowtails.

Lesson plan by Heather Taylor, teachoutside@gmail.com. You are welcome to share all materials with credit to her.