R.K. Kohli, head of the botany department of PU, told IANS: 'There are plenty of cassia siamea and chukrasia tabularis trees in Chandigarh, especially on Madhya Marg and in PU campus. They attract butterflies and are a good source of food for them.'

'Cassia siamea is an ornamental tree with colourful flowers. Butterflies are attracted towards the colour and nectar of its flowers. Whereas chukrasia has no flowers but its dense shade is the best place for butterflies to take shelter,' added Kohli.

Kohli agreed that this year there has been a marked increase in the number of butterflies in and around Chandigarh. He attributed it to increased humidity in the environment, which is a most suitable condition for their breeding.

Even the city-based environmentalists and youngsters are quite enthused on seeing these pretty creatures.

'Every year we wait for these months when we can see butterflies in good number. We also organise workshops for students during which we sit near the trees and discover different species of butterflies,' Rohit Ruhella, an environmentalist based here, told IANS.

'This phenomenon will continue for at least the next couple of months,' he added.

Sidharatha Sharma, a student of fine arts, said: 'It's quite refreshing to see hundreds of butterflies all together. Along with my friends we are also clicking their photographs, and we are planning to organise a photo exhibition of butterflies in the coming days.'

(Alkesh Sharma can be contacted at alkesh.s@ians.in)