The Black Swallowtail butterfly (also known as the Eastern Black Swallowtail) is a common and beautiful butterfly in North America. It is found East of the Continental Divide. It has a western "version" known as the Anise Swallowtail. Both the Black and Anise Swallowtails are popular for raising indoors. Although the Anise and the Black Swallowtail butterflies are different in appearance, their host plants, caterpillars and pupas are nearly identical. This article focuses on general information about Black Swallowtails. If you are looking for specific information about raising these beauties indoors then please see the links at the end of this article.
The Black Swallowtail butterfly lays its eggs on their host plants which are plants in the carrot family such as carrots, parsley, dill, celery, fennel, rue, Queen Anne's Lace (Anise Swallowtails also use Anise as a host plant). The Black Swallowtail eggs are a pale yellow or cream color and are spherical. They lay single eggs rather than clusters and usually on the top of the leaf in the case of parsley.
Black & Decker Drill
The caterpillar will hatch out of the egg in about 5 days and the egg will turn black shortly before this happens. The Black Swallowtail caterpillar changes its appearance quite a bit as it rapidly grows over the next few weeks. It will molt several times and each new exoskeleton is considerably different.
One very interesting feature that all Swallowtail caterpillars share is a prong-shaped organ called the osmeterium which pops out right behind their head when they are disturbed. The osmeterium of the Black Swallowtail caterpillar is bright orange. Osmeteriums release a smelly odor meant to keep predators away.
After about 2-3 weeks the caterpillar will be ready to pupate. The Swallowtails chrysalises do not hang like the chrysalises of many other butterflies. Instead, they are attached to a stem or stick in the same fashion as a telephone pole repairman attaches to a pole. They attach their base to a pad of silk then use a sling of silk to hold them on the stick. The chrysalis will be green or brown depending if they are attached to a green stem or a brown stick. They blend in quite well.
The chrysalis is the life cycle stage in which the Black Swallowtail overwinters. The adult butterflies only live for about 2 weeks or less but as a chrysalis they can go into diapause and overwinter until the following spring when the butterfly emerges, mates, lays eggs, and the cycle begins again. They will complete a few life cycles over the summer until the fall comes and the chrysalises go into diapause.
Assuming the chrysalis has not gone into diapause the adult butterfly will emerge from the chrysalis in 1-2 weeks to begin the fascinating life cycle of the beautiful Black Swallowtail Butterfly once again.