The Plain Tiger butterfly is a tough survivor, pretty and profuse, even in urban areas
Isn’t it odd that in a city that’s increasingly concretised, the Plain Tiger butterfly is thriving? That’s because their choice of larval host plants (food for caterpillars) — milkweed (aak in Hindi).
These plants contain toxins — cardenolides in the case of milkweed — that make the caterpillar as well the butterfly unpalatable. This plant also aids in the survival of the Painted Grasshopper and other insects. In fact, tribes across the world use the poison in the plant on arrow-heads to aid in hunting.
The vibrant colouration of the Plain Tiger sends a warning signal to its predators — birds, lizards — that they could be toxic. This defence mechanism is known as aposematism. The colouration is mimicked by other species like the female Danaid Eggfly butterfy that often move with Plain Tiger butterflies to avoid being eaten alive. This is another of nature’s defence mechanisms, called Batesian Mimicry. Yet another survival mechanism is the haphazard zig-zag flight that the butterfly has, to avoid capture.
The Plain Tiger (Danaus chrysippus) is a medium-sized vibrant butterfly with orange on the upperside with wings edged with black and white. The segmented body (head, thorax and abdomen) is black. The underside of the wings are a lighter shade of orange.
The Plain Tiger belongs to Nymphalidae, the largest family of butterflies with over 6,000 species. It is capable of adapting to a wide variety of habitats across the country: arid, open areas, deciduous forests, urban territory, and others.
Soon after mating, the female Plain Tiger butterfly lays ridged dome-shaped eggs singly on the underside of the larval host plant, to avoid detection by predators. Depending on the weather conditions, the egg may hatch between three and five days. When ready to hatch, the larva inside the egg busts open the shell and comes out before devouring it. The caterpillar feeds voraciously on all parts of the plant and rapidly grows too big for its outer skin. During this process, a layer of newer skin is formed under the old skin, thereby entering the next stage of growth called instar.
A Plain Tiger caterpillar develops through five instar stages with varying sizes and the differences in physical appearance at least until the third instar.
Once the larva reaches the final instar, it stops eating and looks for a convenient place to pupate. It spins a silk pad, suspends itself from it and remains motionless for a couple of hours before shedding its skin one last time, then forminga pupa. Initially the pupa of the Plain Tiger is green with a black line with golden circles on it.
A day before the butterfly is ready to emerge, you can see the colours of the butterfly from the outside. It then splits open the pupa, slowly coming out, clinging to the branches of the plant, dries off completely, and makes its first flight.
Regardless of the stage the butterfly is in, it deals with several dangers for survival, considering that it is prey for a plethora of predators around. Their toxic nature, due to their diet, makes them one of the commonest butterflies in India.
September is Butterfly Month, and for the first time in four years, it’s going all-India, organised by Bombay Natural History Society, in collaboration with NINOX – Owl about Nature, and the Delight Factory from Delhi, partnering with 26 organisations dedicated to the cause. Get in touch with us at email@example.com for guidelines on how to submit your entries.
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 of WWF India.