Why is pieridae flying in the vegetable field?

The cabbage butterfly is the common name for the butterfly Pieris rapae. As the name suggests, it’s closely associated with cabbage. While we may sometimes find them fluttering among flowers, more often, they hover over vegetable patches, especially favoring areas planted with cabbage, bok choy, mustard greens, kale, turnips, and other cruciferous vegetables. These vegetables all belong to the Brassicaceae family.

Why does the cabbage butterfly have a particular fondness for cruciferous vegetables? What special stimuli do these plants possess that attract the butterfly?

According to chemical analysis, these plants contain a substance called mustard oil, which emits an odor that’s highly attractive to butterflies for oviposition. Some have conducted experiments by placing paper soaked in cabbage juice in the field, which still managed to attract cabbage butterflies to lay eggs without hesitation. However, when cabbage butterflies have their antennae removed, their response is different; they lose the ability to choose cruciferous vegetables for oviposition. This indicates that the cabbage butterfly’s preference for vegetable patches is due to the sensitivity of its olfactory nerves in the antennae to the stimulating odor of mustard oil, thus prompting them to fly there for oviposition.