During the first year of our nature trails back in 2016-17, when I pointed out Danaid Eggfly butterflies to people, we saw far more males than females. In time, I realised that not being able to see females was because they have a greater responsibility towards the survival of their species, while the males role is restricted to mating. For this reason, the Danaid Eggfly (Hypolimnas misippus) an evolutionary adaptation. The females mimic (in appearance) the similar-sized Plain Tiger, a toxic butterfly with the toxic Milkweed as its host plant.
The vibrant colours of the Plain Tiger advertise its unpalatable nature to predators around, so the Danaid female sends out the same signal, regardless of it not being toxic. This mimicking is called Batesian Mimicry, named after an English Naturalist, Henry Walter Bates for his work on butterflies. To aid this behaviour, the females also sometimes tend to move with plain tiger butterflies. There are very minute differences in appearance of the two butterflies. The males in this species are elegant to look at with the upperside black with large white oval discs on both wings and yellowish brown undersides.
They tend to fly higher and faster than the females, who prefer being close to the ground. When disturbed, the males quickly gain height to reach a tree branch, whereas females tend to move to nearby bushes.
A scheduled butterfly protected under the Wildlife Protection Act of India, 1971, the Danaid Eggfly belongs to the largest family of butterflies, Nymphalidae. The butterflies in this family are also called Brush-footed Butterflies, where the forelegs (first pair of legs) are reduced in size and covered with long hair, much like brushes.
Butterflies need both nectar-rich plants (like Periwinkle or Sadabahaar) as food sources as well as host plants (where they lay eggs) to survive. These butterflies are known to frequent urban parks and botanical gardens to feed on flowering plants, though they prefer open country, both scrubland and moist areas.
When the females are ready to lay eggs, they look for host plants like the Philippine Violet, also commonly known as Vajra Danti in Hindi.
The best time to see butterflies is when the sun is up and shining.
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.