The sheer and utter incomprehensibility of life and its scope never ceases to confound us. Amongst the countless species in our tiny blue planet, the life cycle of a butterfly is a particularly curious case: how is one to explain that a caterpillar which has grown from a minute pupa, would grow further to the point of spurting out wings? Of late, the city has been witnessing their visual cacophony, outside balconies, or office windows, as they migrate. Hordes of various species were seen in areas like JP Nagar, Koramangala, and Indiranagar.
Monsoon Migration
As Shonali Chinniah, director and owner at Curiouscity Science Centre, explains, “Butterflies, particularly Dark Blue Tiger, Blue Tiger, Common Crow, and Double Branded Crow migrate seasonally in response to the monsoon cycle. Studies highlight that these butterflies travel from the Western Ghats to the Eastern Ghats, between May and June, to avoid the torrential South-West monsoon that hit their larval habitats in the Western Ghats. Their migration ensures survival by allowing them to breed alternately in the plains and in the hills. During October through November they migrate back from the Eastern to the Western Ghats.” Lepidopterist Rohit Girotra adds that ‘the migration depends on the intensity and duration of the monsoon’.
Why Bengaluru?
The predominance of this phenomenon in Bengaluru has two reasons behind it: its geography falling on the East to West migration corridor, and the city’s existing butterfly population. “Bengaluru being located right about the centre of peninsular India, happens to be on the migratory path. Around 120 species have been documented from the city and this includes uncommon ones such as the Lilac Silverline, which was reported from the Hesaraghatta grassland after years. The butterfly diversity in the city has also been shaped by the planting of greenery and maintaining parks and gardens,” says Seshadri KS, a faculty member at Ashoka Trust for Research in Ecology and the Environment, Srirampura. Anil Chinniah, also an owner and director at Curiouscity, adds, “The city’s urban greenery provides temporary resting spots, and the presence of milkweed plants supports their survival. Additionally, the climate during pre-monsoon and post-monsoon periods offers ideal conditions.”
Pressing Threats
The effects of urbanisation have taken a hit in Bengaluru over the years, without much notice. “The main causes include loss of host plants due to urbanisation and habitat fragmentation. Each butterfly species has a limited number of host plants it can lay its eggs. Butterflies like the Lemon Emigrant struggle as their food sources are disappearing due to landscaping,” rues Anil.
At this juncture, conservation is crucial. Curiouscity, JP Nagar and Butterfly Park, Bannerghatta are great sites inviting folks to marvel at the fascinating creatures, with the former hosting guided walks till June 15 from 10am to 3pm (tickets are priced at ₹100 per adult & ₹50 per child). “All one has to do to watch butterflies is to observe them without trying to catch them. Binoculars may be handy. There are several field guides for butterflies which can be used to learn to identify them,” Seshadri states.