Go butterfly-spotting in Thane

Prepare to be greeted by a riot of colourful, fluttering wings on Sunday. The Bombay Natural History Society (BNHS) is taking you to Ovalekar Wadi, the only open-air butterfly garden near the city, which is teeming with magnificent butterflies.

The garden, situated in Owla Village off Ghodbunder Road, was started by Rajendra Ovalekar a few years ago on two acres of agricultural land that belonged to him.

"There are 150 butterfly species found in Mumbai, of which you might spot around 120 in the garden," says butterfly expert and author Isaac Kehimkar, who will be leading the walk.

Among the ones you can expect to sight are the Blue Tiger, Blue Mormon, Blue Oakleaf, Common Baron, Great Orange Tip, and more. You will also learn about the mimicry and camouflaging techniques some of these use to evade predators.

Kehimkar picks six butterflies you might meet this weekend.

Common Jezebel, Delias eucharis
The markings on this butterfly are stunning, but it is toxic and exudes a stench to keep predators away. It does this by feeding on poisonous plants and accumulating toxins when in the larval stage. Moreover, its bright colours are meant to indicate that it is unpalatable. If a bird ends up eating a Common Jezebel, it will start vomiting violently and possibly never go near one again.

Common Silverline, Spindasis vulcanus
This small butterfly gets its name from the silvery markings that appear along the stripes on its wings. The Common Silverline is interesting to observe in its caterpillar form. This is because the caterpillar has a special gland at the end of its abdomen that secretes a sweet liquid. This attracts ants towards it, which, in turn, act as unintentional bodyguards to the caterpillar.

Blue Mormon, Papilio polymnestor
The Blue Mormon is the state butterfly of Maharashtra. It is one of the largest butterfly species, and can be found around Matheran. Constant heavy rain drives it down towards Mumbai. It arrives in July, and leaves by November. But it's not the same butterfly that returns; it's the third or fourth generation. All butterflies have host plants; for the Blue Mormon, it is the citrus family.

Blue Oakleaf, Kallima horsfieldii
The scales on the top of this butterfly's wings are a brilliant blue. However, it resembles a dry leaf when its wings are shut. This is a classic example of mimicry in nature. This sort of camouflage helps the butterfly escape predators. For instance, when a bird starts chasing the Blue Oakleaf, it only sees the flashing blue amidst the steady beating of wings. The butterfly escapes by dropping down into the foliage and closing its wings, so while the bird continues searching for its blue-hued prey, the butterfly could be right under its beak, completely unrecognisable. Another interesting fact about this butterfly is that it lays its eggs on the karvi plant, and this is what the caterpillars later feed on.

On: October 9, 7 am to 12.30 pm
At: Ovalekar Wadi Butterfly Garden, Ghodbunder Road, Thane (W). Bus will leave from Dadar TT (near Chandu Halwai) at 7 am, Chembur (near Diamond Garden) at 7.20 am, and Thane (Cadbury Junction) at 7.40 am.
Cost: 800 (BNHS members), 900 (non-members). Cost includes transport and BNHS expertise only. Carry packed food, a hat and rain gear
Call: 22821811