Bangkok: Let's get to know the vibrant colors of the open forest and the rainy season. Have you ever noticed those yellow butterflies that often flutter around in front gardens or gather in swarms on damp ground? What kind of butterflies are they? Today, we'll introduce you to the "Common Cassia Butterfly," a colorful creature of the rainy season that can be found all around us!
According to Thai News Agency, the "Common Emigrant" (Lemon Emigrant) is a medium-sized butterfly in the family Pieridae. It is one of the most common and abundant butterflies found throughout Thailand, inhabiting open forests, parks, and even urban areas with its host plants. An extraordinary phenomenon: one species, but six different patterns! This butterfly has a wingspan of approximately 55-80 millimeters and wings of pale yellow, bright yellow, or pale greenish-yellow. The amazing thing is their high genetic diversity, resulting in six distinct coloration and pattern variations. Some may have thick black wing edges, while others have hidden reddish-brown spots under their wings.
A simple way to distinguish sexes: Males usually have yellowish-white or pale yellow wings with a small black edge. Females have a brighter, more intense yellow color and often have a prominent circular spot in the center of the forewings.
These swift, forest-dwelling birds may be small, but they are incredibly fast and agile. Their behavior of flying in large flocks on wet ground or along stream banks to feed on nutrients, a phenomenon known as "salt licking," can be observed year-round, but they are especially abundant during the early rainy season, around June. Nature photography enthusiasts shouldn't miss this!
The name "Koon Worm" isn't chosen lightly because, in its infancy, the caterpillars of this butterfly species are obsessed with eating the leaves of legumes, especially the Cassia fistula (Golden Shower Tree), Cassia siamea, and Cassia siamea trees, which are considered its staple food.
Information and images from: Khlong Lan National Park, Kamphaeng Phet Province, Conservation Area Administration Office 12 (Nakhon Sawan).