You’ve probably seen the beautiful Lime Butterfly if you have a Chinese Orange ( Citrus medica ), Ber (Zizyphus mauritiana), or Bael (Aegle Marmelos) plant in your backyard. The butterfly that belongs to the Swallowtail group, and is often called the Lime Swallowtail, lays its eggs on these and other citrus plants. It is one of the bigger butterflies found in our region with an impressive wingspan of about 80-100mm.
The family of swallowtails showcases some of the most spectacular butterflies in the world and most of the species have hind wings that have a forked appearance. The Lime is an exception. The pattern on its wings is chequered with irregular spots and patches of white, black, yellow, green and two orangish-red markings on the edges of the hindwings.
The butterfly is a mud-puddler. Mud-puddling is a behaviour exhibited by butterflies and a few other insects, where they sit on moist soil and dung, and suck up the fluid to extract certain salts and nutrients that play an important role in their life-processes. Seen basking with its wings held wide open on plants, it’s usually a low flier.
The Lime Butterfly as a caterpillar
The female butterfly goes from plant to plant, laying a single egg, like most other swallowtails. The caterpillar has five Instars (stages): the first when it emerges from the egg (black in colour), the second, third, and fourth when it outgrows its outer skin and sheds it in order to accommodate its size. At these stages, it’s dark with white markings on the body, resembling uric acid. This makes it look like bird droppings, helping it to escape predators. In the final stage, the caterpillar assumes a cylindrical shape, uniformly pale green, with some amount of white on its body.
Most swallowtail caterpillars have a forked organ called the osmeterium at the base of the head, on the back. When threatened, the osmeterium pops out and releases a pungent smell of butyric acid, mainly to evade ants, parasitic wasps, and flies. The Lime butterfly is no exception.
Despite their camouflaging prowess, a few caterpillars are found by parasitic wasps. These wasps lay dozens of eggs inside of the caterpillars. The wasp-larvae feed on the butterfly caterpillar from the inside. The vital organs are spared at first to keep the caterpillar alive until it’s ready to pupate, after which even those are consumed. Shortly before or soon after the pupation process, the wasp parasitoids emerge from their host, thus killing it.
The widespread range of this butterfly indicates its tolerance and adaptation to diverse habitats as we can see them in gardens, farmlands and sometimes forest patches. Every September is celebrated as Butterfly Month.
The writer is the founder of NINOX - Owl About Nature, a nature-awareness initiative. He is the Delhi-NCR reviewer for Ebird, a Cornell University initiative, monitoring rare sightings of birds. He formerly led a programme at WWF India.
