Butterflies have been studied in Nepal for over 150 years, with much of the original study and collection done by the British, including one or two British Residents (i.e. British Consuls of the day). After 1950 the Japanese became involved in collection through scientific expeditions, and this resulted later in the establishment by Tribhuvan University of the Natural History Museum at Swayambhu in 1974.
The record books state that Nepal has 11 out of the 15 families of butterflies in the world, or over 500 species, and still today in the 21st century new species keep turning up. It is said that you never really know with Nepal’s butterflies; they just may turn up unexpectedly. From 1974 to 1981, only a period of seven years, a further 24 specimens or sub-families were added to the records, and in 1981 two alone, the BLUE DUCHESS and the SIKKIM HAIRSTREAK were discovered, with this last one known only from a single specimen from Sikkim, with this one female found in 1981 in Godavari, Kathmandu Valley; and later in 1986 an entirely new race of the CHINESE HAIRSTREAK turned up.
The original collectors were not allowed outside the Kathmandu Valley, so much of their research documented only the valley. Only after 1950 when Nepal opened up to expeditions and limited tourism, did the butterfly collectors venture outside the valley.
Nepal is divided into 5 regions based on altitude, and the seasons are specified as spring, Pre-monsoon, Summer-monsoon, Post-monsoon, autumn and Winter. In winter there is very little activity except for the very common Oriental Species, with the distribution of butterflies in Nepal being quite specific with about 10% of the butterflies being Palaearctic species above 3,000 metres, and about 90% Oriental species below 3,000 metres.
Within the Kathmandu Valley, the climate which is quite mild with day temperatures reaching 18ÂºC in mid-winter, there are butterflies all the year round. The best seasons for butterfly watching are late March/April, mid May/ mid June, late August/September. There are forested areas in the valley which are still remarkable places for butterflies, and they include open country near Chobar and Swyambhu; the base of the hills and forest streams at Godavari, Nagarjun, Budhanilkantha and Sundarijal; the forested hilltops of Phulchowki, Jamachowk and Shivapuri, and the open scrubby bush areas of Nagarkot, Suryavinyak and Chandragiri.
There are about 20 Kathmandu Valley species on the endangered or vulnerable list. Outside the valley in the areas of the National Parks scattered throughout the country, the butterflies too are in profusion, and in undisturbed areas away from settlements are the ideal places to sit and watch.