A bright, yellow caterpillar with gray spots and big black eyes was found by one of our readers. She did not pose any question, but simply wanted to share these excellent photos with us. This article will address what this caterpillar is in case any of our other readers happens upon one.
This dazzling, bright yellow caterpillar is that of the spicebush swallowtail. This butterfly is black when fully matured, with white spots on the topside of its dark blue or green wings, and orange spots on the underside. When in its larval form, it can be bright yellow as in the case of the one our reader found, but can also be a vibrant green color. During the day, these caterpillars tend to hide under leaves, and come out to feed during the night, so our reader is lucky to have found one out in the open in the middle of the day. Their natural habitats consist of woodlands, swamps, and fields. Like most caterpillars, these caterpillars feed on leaves, and according to GardeningWithWings spicebush swallowtail caterpillars are particularly attracted to nectar plants and “host plants”, which are a category of plants that generally attract butterflies to one’s garden. It can thus be assumed that given this source’s positive attitude toward these caterpillars, they are not pests.
Examples of nectar plants they can be found on or near are milkweed, sunflowers and butterfly bush, and examples of host plants are flowers such as aster, rue, violet, herbs such as dill, fennel, and parsley, and trees such as aspens, pawpaws, and willows. These are only a fraction of the host plants that can attract butterflies, all of which can be found on the website linked in the paragraph above.
Spicebush swallowtails can be found all over the Eastern United States, and are not to be confused with black swallowtails, which are found almost all over the United States and in Mexico. While the black swallowtail looks very similar in its matured form, their caterpillars are green, with black and yellow-dotted stripes, and also thinner black stripes in between those stripes. In their matured forms, a slight difference in wing pattern is the indicator one should look for to differentiate the two species.
In conclusion, we wish to thank our reader for providing such excellent photos of this spicebush swallowtail caterpillar. These creatures are not only beautiful, but utterly harmless, and considered a “welcome visitor to any garden” (GardeningWithWings).